Indications for accurate and appropriate use of personal protective equipment for healthcare professionals. A systematic review

Maria Stella Peccin Márcio Luís Duarte Aline Mizusaki Imoto Mônica Taminato Humberto Saconato Maria Eduarda Puga Eduardo Signorini Bicas Franco Erika Barbosa Camargo Leila Bernarda Donato Gottems Álvaro Nagib Atallah About the authors

ABSTRACT

BACKGROUND:

The speed of the spread of coronavirus disease 2019 (COVID-19) has put enormous pressure on hospitals and other healthcare facilities. This, together with blockages in several countries, has hindered the availability and accessibility of the necessary personal protective equipment (PPE).

OBJECTIVE:

To identify, systematically evaluate and summarize the available scientific evidence on the efficacy, safety, safe use and reuse of PPE for healthcare professionals, for preventing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

DESIGN AND SETTING:

Systematic review of studies analyzing products for disinfecting and enabling reuse of PPE for coronavirus within the evidence-based health program of a federal university in São Paulo (SP), Brazil.

METHODS:

A systematic search of the relevant literature was conducted in the PubMed, EMBASE, Cochrane Library, CINAHL, SCOPUS, Web of Science and LILACS databases, for articles published up to November 30, 2020.

RESULTS:

Ten studies were selected. These analyzed the use of N95, surgical and cotton masks, face shields, flexible enclosures with plastic covers or polycarbonate intubation boxes and plastic curtains; and also PPE disinfection using several substances.

CONCLUSION:

Combined use of a face shield with a N95 mask proved to be superior to other associations for protecting healthcare workers. Some products are useful for disinfecting PPE, such as 70% ethanol, 0.1% sodium hypochlorite and a mixture of quaternary ammonium and H2O2, and hydrogen peroxide. Ultraviolet light and dry heat at 70 °C can be used to decontaminate N95 masks.

REGISTRATION NUMBER:

DOI: 10.17605/OSF.IO/4V5FD at the OPENSCIENCE Framework.

KEYWORDS (MeSH terms):
COVID-19 [supplementary concept]; Coronavirus infections; Disinfection; Respiratory

AUTHORS KEYWORDS:
SARS-CoV-2; Mask disinfection; Face shield disinfection

INTRODUCTION

The pandemic caused by coronavirus disease 2019 (COVID-19) is severely affecting healthcare systems worldwide, including the care of several chronic diseases, such as cancer.11. Taminato M, Mizusaki-Imoto A, Saconato H, et al. Homemade cloth face masks as a barrier againstrespiratory droplets - systematic review. Acta Paul Enferm. 2020;33:eAPE2020010. https://doi.org/10.37689/acta-ape/2020ar0103.
https://doi.org/https://doi.org/10.37689...
,22. Duarte ML, Santos LRD, Contenças ACS, et al. Reverse-transcriptase polymerase chain reaction versus chest computed tomography for detecting early symptoms of COVID-19. A diagnostic accuracy systematic review and meta-analysis. Sao Paulo Med J. 2020;138(5):422-32. PMID: 32844901; https://doi.org/10.1590/1516-3180.2020.034306072020.
https://doi.org/32844901https://doi.org/...
,33. Marques NP, Silveira DMM, Marques NCT, et al. Cancer diagnosis in Brazil in the COVID-19 era. Semin Oncol. 2021:S0093-7754(20)30123-8. PMID: 33478743; https://doi.org/10.1053/j.seminoncol.2020.12.002.
https://doi.org/33478743https://doi.org/...
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the agent that causes COVID-19, is a respiratory virus transmitted through droplets and by contact. It can be disseminated through aerosolization, swab collection, intubation, aspiration, noninvasive ventilation, high-flow nasal cannulas and bag-mask ventilation.44. Shimabukuro PMS, Duarte ML, Imoto AM, et al. Environmental cleaning to prevent COVID-19 infection. A rapid systematic review. Sao Paulo Med J. 2020;138(6):505-14. PMID: 33206913. https://doi.org/10.1590/1516-3180.2020.0417.09092020.
https://doi.org/33206913https://doi.org/...
,55. Cheung JC-H, Ho LT, Cheng JV, Cham EYK, Lam KN. Staff safety during emergency airway management for COVID-19 in Hong Kong. Lancet Respir Med. 2020;8(4):e19. PMID: 32105633; https://doi.org/10.1016/S2213-2600(20)30084-9.
https://doi.org/32105633https://doi.org/...
Prevention and control measures for the new coronavirus need to include hand hygiene, disinfection of surfaces (notably those frequently touched), avoidance of touching the face, respiratory manners (covering the mouth while coughing) and use of masks.11. Taminato M, Mizusaki-Imoto A, Saconato H, et al. Homemade cloth face masks as a barrier againstrespiratory droplets - systematic review. Acta Paul Enferm. 2020;33:eAPE2020010. https://doi.org/10.37689/acta-ape/2020ar0103.
https://doi.org/https://doi.org/10.37689...
,44. Shimabukuro PMS, Duarte ML, Imoto AM, et al. Environmental cleaning to prevent COVID-19 infection. A rapid systematic review. Sao Paulo Med J. 2020;138(6):505-14. PMID: 33206913. https://doi.org/10.1590/1516-3180.2020.0417.09092020.
https://doi.org/33206913https://doi.org/...
,66. MacIntyre CR, Chughtai AA. A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients. Int J Nurs Stud. 2020;108:103629. PMID: 32512240; https://doi.org/10.1016/j.ijnurstu.2020.103629.
https://doi.org/https://doi.org/10.1016/...

The speed of the spread of COVID-19 has put enormous pressure on hospitals and other healthcare facilities.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
This, together with blockages in several countries, has hindered availability and accessibility regarding the necessary personal protective equipment (PPE).77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
The Centers for Disease Control and Prevention (CDC) of the United States recommends the use of gloves, aprons, respiratory protection (e.g. disposable N95 respirators) and eye protection (e.g. goggles or face shields), without the use of shoe protectors (props).88. Ong SWX, Tan YK, Sutjipto S, et al. Absence of contamination of personal protective equipment (PPE) by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Infect Control Hosp Epidemiol. 2020;41(5):614-6. PMID: 32213231; https://doi.org/10.1017/ice.2020.91.
https://doi.org/https://doi.org/10.1017/...
According to a meta-analysis by Li et al.,99. Li Y, Liang M, Gao L, et al. Face masks to prevent transmission of COVID-19: A systematic review and meta-analysis. Am J Infect Control. 2020:S0196-6553(20)31043-9. PMID: 33347937; https://doi.org/10.1016/j.ajic.2020.12.007.
https://doi.org/https://doi.org/10.1016/...
use of face masks decreased the risk of COVID-19 infection by 70%, for healthcare workers.

PPE in healthcare is generally considered to be part of what is called transmission-based precautions.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...
Standard precautions or universal precautions are based on the principle that all blood, body fluids, secretions, excretions other than sweat, non-intact skin and mucous membranes can contain transmissible agents for infectious diseases.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...
Depending on the expected exposure, hand hygiene and the use of PPE, such as gloves, aprons, masks, caps or eye protection (i.e. goggles or face protection) should be implemented.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...
According to the World Health Organization, more than 59 million people work in the healthcare sector worldwide.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...
These healthcare professionals are at risk of developing life-threatening infectious diseases through contact with patients’ blood or body fluids, such as mucus, vomit or exhaled drops.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...

Sprays and splashes of fluids containing infectious microorganisms represent an occupational risk for healthcare professionals.1111. Lindsley WG, Noti JD, Blachere FM, Szalajda JV, Beezhold DH. Efficacy of face shields against cough aerosol droplets from a cough simulator. J Occup Environ Hyg. 2014;11(8):509-18. PMID: 24467190; https://doi.org/10.1080/15459624.2013.877591.
https://doi.org/https://doi.org/10.1080/...
The droplets of these fluids can be inhaled, come into contact with damaged skin or be deposited on the mucous membranes of the mouth, nose or eyes.1111. Lindsley WG, Noti JD, Blachere FM, Szalajda JV, Beezhold DH. Efficacy of face shields against cough aerosol droplets from a cough simulator. J Occup Environ Hyg. 2014;11(8):509-18. PMID: 24467190; https://doi.org/10.1080/15459624.2013.877591.
https://doi.org/https://doi.org/10.1080/...
Once in these structures, pathogens can infect workers and cause disease.1111. Lindsley WG, Noti JD, Blachere FM, Szalajda JV, Beezhold DH. Efficacy of face shields against cough aerosol droplets from a cough simulator. J Occup Environ Hyg. 2014;11(8):509-18. PMID: 24467190; https://doi.org/10.1080/15459624.2013.877591.
https://doi.org/https://doi.org/10.1080/...
It should be considered that small aerosol droplets from a patient with a cough can remain in the air and spread throughout a room, and can easily be inhaled by a healthcare professional.1111. Lindsley WG, Noti JD, Blachere FM, Szalajda JV, Beezhold DH. Efficacy of face shields against cough aerosol droplets from a cough simulator. J Occup Environ Hyg. 2014;11(8):509-18. PMID: 24467190; https://doi.org/10.1080/15459624.2013.877591.
https://doi.org/https://doi.org/10.1080/...
,1212. Liang K. Mathematical model of infection kinetics and its analysis for COVID-19, SARS and MERS. Infect Genet Evol. 2020;82:104306. PMID: 32278147; https://doi.org/10.1016/j.meegid.2020.104306.
https://doi.org/https://doi.org/10.1016/...

The risk of infection and its consequences are variable but are well recognized as an occupational risk.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...
However, in epidemics, the risk of infection is higher because of the higher infection rate among healthcare professionals than among the general population.55. Cheung JC-H, Ho LT, Cheng JV, Cham EYK, Lam KN. Staff safety during emergency airway management for COVID-19 in Hong Kong. Lancet Respir Med. 2020;8(4):e19. PMID: 32105633; https://doi.org/10.1016/S2213-2600(20)30084-9.
https://doi.org/32105633https://doi.org/...
,1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...
The variable clinical spectrum of COVID-19 needs to be considered: given that the majority of cases are asymptomatic or oligosymptomatic,22. Duarte ML, Santos LRD, Contenças ACS, et al. Reverse-transcriptase polymerase chain reaction versus chest computed tomography for detecting early symptoms of COVID-19. A diagnostic accuracy systematic review and meta-analysis. Sao Paulo Med J. 2020;138(5):422-32. PMID: 32844901; https://doi.org/10.1590/1516-3180.2020.034306072020.
https://doi.org/32844901https://doi.org/...
infection can be passed from an asymptomatic healthcare professional to a patient with any other disease, or it can even be passed among the patients themselves.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...
Furthermore, if healthcare professionals become infected, this decreases the capacity of the healthcare system to provide care, particularly at times of epidemic, when it is overburdened.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...

This situation was previously experienced in 2002 and 2003, during the epidemic of the severe acute respiratory syndrome (SARS), in which 20% of all patients were healthcare professionals and about 10% lost their lives.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...
,1313. World Health Organization (WHO). Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003. available from: available from: http://www.who.int/csr/sars/country/table2004_04_21/en/ . Accessed in 2021 (Apr 30).
http://www.who.int/csr/sars/country/tabl...
,1414. Bartoszko JJ, Farooqi MAM, Alhazzani W, Loeb M. Medical masks vs N95 respirators for preventing COVID-19 in healthcare workers: A systematic review and meta-analysis of randomized trials. Influenza Other Respi Viruses. 2020;14(4):365-73. PMID: 32246890; https://doi.org/10.1111/irv.12745.
https://doi.org/https://doi.org/10.1111/...
The scarcity of PPE and its ineffective implementation were the main reasons behind the high number of healthcare professionals who became infected at the beginning of the COVID-19 pandemic.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
In March 2020, Remuzzi et al. reported that a fifth of healthcare professionals working in intensive care units (ICUs) were infected with COVID-19.1515. Remuzzi A, Remuzzi G. COVID-19 and Italy: what next? Lancet. 2020;395(10231):1225-8. PMID: 32178769; https://doi.org/10.1016/S0140-6736(20)30627-9.
https://doi.org/https://doi.org/10.1016/...
Giwa et al. estimated that at least 10% of healthcare professionals in Italy would become infected with ­COVID-19 despite their use of PPE.1616. Giwa AL, Desai A, Duca A. Novel 2019 coronavirus SARS-CoV-2 (COVID-19): An updated overview for emergency clinicians. Emerg Med Pract. 2020;22(5):1-28. PMID: 32207910. In a case series analyzed by Wang et al., out of 138 consecutive patients who were hospitalized due to COVID-19 in Wuhan, China, during January 2020, 30% were healthcare professionals.1717. Wang D, Hu B, Hu C, et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. JAMA. 2020;323(11):1061-1069. PMID: 32031570; https://doi.org/10.1001/jama.2020.1585.
https://doi.org/https://doi.org/10.1001/...

In January 2020, the CDC released guidelines on the decontamination process for reusing N95 masks.1818. Centers for Disease Control and Prevention. Decontamination & Reuse of N95 Respirators. Available from: Available from: https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html . Accessed in 2021 (Apr 30).
https://www.cdc.gov/coronavirus/2019-nco...
A variety of procedures can be followed for reusing these masks, but none of the known methods completely remove the associated risks.1818. Centers for Disease Control and Prevention. Decontamination & Reuse of N95 Respirators. Available from: Available from: https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html . Accessed in 2021 (Apr 30).
https://www.cdc.gov/coronavirus/2019-nco...
The existing systematic reviews refer only to use of masks in relation to the COVID-19 pandemic.1414. Bartoszko JJ, Farooqi MAM, Alhazzani W, Loeb M. Medical masks vs N95 respirators for preventing COVID-19 in healthcare workers: A systematic review and meta-analysis of randomized trials. Influenza Other Respi Viruses. 2020;14(4):365-73. PMID: 32246890; https://doi.org/10.1111/irv.12745.
https://doi.org/https://doi.org/10.1111/...
Concerning other types of PPE, such as gloves, glasses and face shields, the existing systematic reviews are not specific to COVID-19, and have included reference to several agents that cause respiratory infections.66. MacIntyre CR, Chughtai AA. A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients. Int J Nurs Stud. 2020;108:103629. PMID: 32512240; https://doi.org/10.1016/j.ijnurstu.2020.103629.
https://doi.org/https://doi.org/10.1016/...
Furthermore, we did not find any systematic reviews on the use of PPE such as gloves, glasses and face shields, for protection against COVID-19.

OBJECTIVES

The objective of the present study was to identify, systematically evaluate and summarize the available scientific evidence regarding the efficacy, safety, duration of use and reuse of personal protective equipment (masks, face shields and glasses) for healthcare professionals, for protection against infection by SARS-CoV-2.

METHODS

Study model

This study was a rapid systematic review. The research protocol was registered on the OPENSCIENCE Framework.

Inclusion criteria

The search was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Concerning the type of studies, given that only a limited number of studies have been published so far, the purpose of this review was to map the knowledge of the subject and identify the designs of these studies according to their level of evidence. There was no restriction on the origin, language or publication status of the study.

Phenomena of interest

Use of PPE (masks, face shields and goggles) for prevention of COVID-19 transmission among healthcare professionals and disinfection of PPE constituted the phenomena of interest.

Types of participants

Except for laboratory studies, the types of participants considered for this systematic review were healthcare professionals in a hospital environment or outpatient setting.

Types of intervention

Studies that evaluated the effectiveness and efficacy of several types of PPE, such as different types of masks, duration of use, use of goggles and face shield protectors, separately or in combination, and other techniques that helped to prevent contamination by COVID-19 among healthcare professionals, were assessed.

Types of outcome

Primary outcomes

The primary outcomes were interventions and disinfecting materials that were effective for preventing COVID-19 contamination.

Secondary outcomes

The secondary outcomes considered were the following:

  • PPE durability

  • User satisfaction

  • Cost

The secondary outcomes were not considered as inclusion criteria for the studies.

Search methods for selecting studies

The search strategy was elaborated starting from the following research question: “What is the degree of effectiveness and safety of personal protective equipment (masks, face shields and glasses) for the protection of healthcare professionals against infection by SARS-CoV-2, and how can this equipment be safely used and reused?”

The searches were elaborated using Health Science Descriptors and were translated into each of the databases selected: Cochrane Library (Wiley); Embase (Elsevier); BVS Portal; Medical Literature Analysis and Retrieval System Online (MEDLINE, PubMed); CINAHL; Web of Science; Scopus; and Opengrey (https://opengrey.eu). The following descriptors were used: severe acute respiratory syndrome coronavirus 2”[Supplementary Concept] OR “severe acute respiratory syndrome coronavirus 2”[All Fields] OR “sars cov 2”[All Fields] AND “Respiratory Protective Devices”[MeSH Terms] or “Masks”[MeSH Terms] AND “Face Shield”[MeSH Terms]

A manual search was also conducted in the reference lists of the primary and secondary studies identified in the electronic search. The search strategies developed and used for each electronic database were performed on November 30, 2020, and are presented in Table 1. There were no restrictions on languages or forms of publication.

Table 1.
Search strategy according to the corresponding database

Selection of studies and data extraction

Identification of eligible studies followed a two-stage process accomplished by two independent reviewers. Any disagreement was resolved by a third reviewer. In the first stage, after exclusion of duplications, the titles and abstracts of the references identified through the search strategy were evaluated, and the potentially eligible studies were preselected. In the second stage, a full-text evaluation on the studies preselected was carried out to confirm their eligibility. The selection process was performed through the Rayyan platform (https://rayyan.qcri.org).1919. Ouzzani M, Hammady H, Fedorowicz Z, Elmagarmid A. Rayyan-a web and mobile app for systematic reviews. Syst Rev. 2016;5(1):210. PMID: 27919275; https://doi.org/10.1186/s13643-016-0384-4.
https://doi.org/https://doi.org/10.1186/...
The details of the ten studies that in the end were selected for evaluation are shown in Table 2.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
,88. Ong SWX, Tan YK, Sutjipto S, et al. Absence of contamination of personal protective equipment (PPE) by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Infect Control Hosp Epidemiol. 2020;41(5):614-6. PMID: 32213231; https://doi.org/10.1017/ice.2020.91.
https://doi.org/https://doi.org/10.1017/...
,2020. Noguera SV, Espinoza EPS, Côrtes MF, et al. Disinfection of 3D-printed protective face shield during COVID-19 pandemic. Am J Infect Control. 2021;49(4):512-5. PMID: 33080363; https://doi.org/10.1016/j.ajic.2020.10.008.
https://doi.org/https://doi.org/10.1016/...
,2121. Sapoval M, Gaultier AL, Del Giudice C, et al. 3D-printed face protective shield in interventional radiology: Evaluation of an immediate solution in the era of COVID-19 pandemic. Diagn Interv Imaging. 2020;101(6):413-5. PMID: 32354631; https://doi.org/10.1016/j.diii.2020.04.004.
https://doi.org/https://doi.org/10.1016/...
,2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
,2323. Chow VLY, Chan JYW, Ho VWY, et al. Tracheostomy during COVID-19 pandemic-Novel approach. Head Neck. 2020;42(7):1367-73. PMID: 32358855; https://doi.org/10.1002/hed.26234.
https://doi.org/https://doi.org/10.1002/...
,2424. Arumuru V, Pasa J, Samantaray SS. Experimental visualization of sneezing and efficacy of face masks and shields. Phys Fluids (1994). 2020;32(11):115129. PMID: 33244217; https://doi.org/10.1063/5.0030101.
https://doi.org/https://doi.org/10.1063/...
,2525. Armijo PR, Markin NW, Nguyen S, et al. 3D printing of face shields to meet the immediate need for PPE in an anesthesiology department during the COVID-19 pandemic. Am J Infect Control. 2021;49(3):302-8. PMID: 32763350; https://doi.org/10.1016/j.ajic.2020.07.037.
https://doi.org/https://doi.org/10.1016/...
,2626. Saini V, Sikri K, Batra SD, Kalra P, Gautam K. Development of a highly effective low-cost vaporized hydrogen peroxide-based method for disinfection of personal protective equipment for their selective reuse during pandemics. Gut Pathog. 2020;12:29. PMID: 32572338; https://doi.org/10.1186/s13099-020-00367-4.
https://doi.org/https://doi.org/10.1186/...
,2727. Smith CR, Gravenstein N, LeMaster TE, Borde CM, Fahy BG. A Flexible Enclosure to Protect Respiratory Therapists During Aerosol-Generating Procedures. Respir Care. 2020;65(12):1923-32. PMID: 33229369. https://doi.org/10.4187/respcare.08568.
https://doi.org/https://doi.org/10.4187/...

Table 2.
Analysis of the articles included in the study

Evaluation of methodological quality

The critical appraisal tool of the Joanna Briggs Institute was applied to all eligible studies in order to evaluate the methodological quality of the studies.

RESULTS

Studies selected

The systematic review yielded 513 papers and a further three papers were identified through manual searches. After removing duplicates, we obtained 389 articles. After the titles and abstracts had been read by two independent evaluators through the Rayyan online platform, 13 articles were included for reading the full text. After the full texts had been read, another three studies were excluded. The PRISMA flowchart is shown in Figure 1. Thus, ten studies were included for analysis. Since these studies refer to COVID-19, all of them were from the year 2020: two were published in June, two in July and one in each of the following months: March, August, September, October, November and December.

Figure 1.
PRISMA flow diagram for study selection.

Characteristics of studies included

The ten studies included all related to COVID-19 and were from the year 2020. Two of them were published in June, two in July and one in each of the following months: March, August, September, October, November and December. One article was produced in Brazil, three in the United States, one in France, one in China, three in India and one in Singapore.

Six studies were cross-sectional (Ong, Chaturvedi, Noguera, Sapoval, Fischer and Chow),77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
,88. Ong SWX, Tan YK, Sutjipto S, et al. Absence of contamination of personal protective equipment (PPE) by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Infect Control Hosp Epidemiol. 2020;41(5):614-6. PMID: 32213231; https://doi.org/10.1017/ice.2020.91.
https://doi.org/https://doi.org/10.1017/...
,2020. Noguera SV, Espinoza EPS, Côrtes MF, et al. Disinfection of 3D-printed protective face shield during COVID-19 pandemic. Am J Infect Control. 2021;49(4):512-5. PMID: 33080363; https://doi.org/10.1016/j.ajic.2020.10.008.
https://doi.org/https://doi.org/10.1016/...
,2121. Sapoval M, Gaultier AL, Del Giudice C, et al. 3D-printed face protective shield in interventional radiology: Evaluation of an immediate solution in the era of COVID-19 pandemic. Diagn Interv Imaging. 2020;101(6):413-5. PMID: 32354631; https://doi.org/10.1016/j.diii.2020.04.004.
https://doi.org/https://doi.org/10.1016/...
,2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
,2323. Chow VLY, Chan JYW, Ho VWY, et al. Tracheostomy during COVID-19 pandemic-Novel approach. Head Neck. 2020;42(7):1367-73. PMID: 32358855; https://doi.org/10.1002/hed.26234.
https://doi.org/https://doi.org/10.1002/...
three studies had laboratory designs (Arumuru, Armijo and Saini)2424. Arumuru V, Pasa J, Samantaray SS. Experimental visualization of sneezing and efficacy of face masks and shields. Phys Fluids (1994). 2020;32(11):115129. PMID: 33244217; https://doi.org/10.1063/5.0030101.
https://doi.org/https://doi.org/10.1063/...
,2525. Armijo PR, Markin NW, Nguyen S, et al. 3D printing of face shields to meet the immediate need for PPE in an anesthesiology department during the COVID-19 pandemic. Am J Infect Control. 2021;49(3):302-8. PMID: 32763350; https://doi.org/10.1016/j.ajic.2020.07.037.
https://doi.org/https://doi.org/10.1016/...
,2626. Saini V, Sikri K, Batra SD, Kalra P, Gautam K. Development of a highly effective low-cost vaporized hydrogen peroxide-based method for disinfection of personal protective equipment for their selective reuse during pandemics. Gut Pathog. 2020;12:29. PMID: 32572338; https://doi.org/10.1186/s13099-020-00367-4.
https://doi.org/https://doi.org/10.1186/...
and one study (Smith) was carried out on a simulation mannequin in an intensive care setting.2727. Smith CR, Gravenstein N, LeMaster TE, Borde CM, Fahy BG. A Flexible Enclosure to Protect Respiratory Therapists During Aerosol-Generating Procedures. Respir Care. 2020;65(12):1923-32. PMID: 33229369. https://doi.org/10.4187/respcare.08568.
https://doi.org/https://doi.org/10.4187/...

Ong et al.88. Ong SWX, Tan YK, Sutjipto S, et al. Absence of contamination of personal protective equipment (PPE) by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Infect Control Hosp Epidemiol. 2020;41(5):614-6. PMID: 32213231; https://doi.org/10.1017/ice.2020.91.
https://doi.org/https://doi.org/10.1017/...
sampled the PPE used by healthcare professionals who cared for patients with COVID-19. Chaturvedi et al.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
surveyed the opinions of 227 orthopedic surgeons and emergency medicine professionals who made use of 3D printed face shields. Noguera et al.2020. Noguera SV, Espinoza EPS, Côrtes MF, et al. Disinfection of 3D-printed protective face shield during COVID-19 pandemic. Am J Infect Control. 2021;49(4):512-5. PMID: 33080363; https://doi.org/10.1016/j.ajic.2020.10.008.
https://doi.org/https://doi.org/10.1016/...
tested chemical disinfectants and autoclaving on 3D printed face shields, and also investigated the comfort, viability and visual integrity of the shields through a questionnaire that was applied to the healthcare professionals who were using them.

Sapoval et al.2121. Sapoval M, Gaultier AL, Del Giudice C, et al. 3D-printed face protective shield in interventional radiology: Evaluation of an immediate solution in the era of COVID-19 pandemic. Diagn Interv Imaging. 2020;101(6):413-5. PMID: 32354631; https://doi.org/10.1016/j.diii.2020.04.004.
https://doi.org/https://doi.org/10.1016/...
conducted a study among 38 interventionist radiologists to assess the visual comfort of 3D printed face shields and these professionals’ tolerance of them and ability to perform interventions normally while using them. Fischer et al.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
analyzed decontamination of N95 masks and the possibility of their reuse. Chow et al.2323. Chow VLY, Chan JYW, Ho VWY, et al. Tracheostomy during COVID-19 pandemic-Novel approach. Head Neck. 2020;42(7):1367-73. PMID: 32358855; https://doi.org/10.1002/hed.26234.
https://doi.org/https://doi.org/10.1002/...
used plastic curtains draped across the patients during tracheostomy and head and neck surgery, with the aim of minimizing the contamination of healthcare professionals from droplets and aerosols emanating from the patients, during the procedures. These authors analyzed the plastic sheets of the curtain and the face shields of the professionals to identify contamination.

Arumuru et al.2424. Arumuru V, Pasa J, Samantaray SS. Experimental visualization of sneezing and efficacy of face masks and shields. Phys Fluids (1994). 2020;32(11):115129. PMID: 33244217; https://doi.org/10.1063/5.0030101.
https://doi.org/https://doi.org/10.1063/...
used a standard laboratory mannequin that simulated sneezing, in order to assess the effectiveness of masks for blocking the particles ejected during sneezing. Armijo et al.2525. Armijo PR, Markin NW, Nguyen S, et al. 3D printing of face shields to meet the immediate need for PPE in an anesthesiology department during the COVID-19 pandemic. Am J Infect Control. 2021;49(3):302-8. PMID: 32763350; https://doi.org/10.1016/j.ajic.2020.07.037.
https://doi.org/https://doi.org/10.1016/...
analyzed protocols for decontaminating 112 face shields, in a laboratory. Saini et al.2626. Saini V, Sikri K, Batra SD, Kalra P, Gautam K. Development of a highly effective low-cost vaporized hydrogen peroxide-based method for disinfection of personal protective equipment for their selective reuse during pandemics. Gut Pathog. 2020;12:29. PMID: 32572338; https://doi.org/10.1186/s13099-020-00367-4.
https://doi.org/https://doi.org/10.1186/...
evaluated the disinfection process for personal protective clothing, N95 masks and face shields, in a laboratory.

Smith et al.2727. Smith CR, Gravenstein N, LeMaster TE, Borde CM, Fahy BG. A Flexible Enclosure to Protect Respiratory Therapists During Aerosol-Generating Procedures. Respir Care. 2020;65(12):1923-32. PMID: 33229369. https://doi.org/10.4187/respcare.08568.
https://doi.org/https://doi.org/10.4187/...
conducted a simulation study in an ICU, among three healthcare professionals, to assess the risk of contamination of professionals and the use of PPE with three different protection strategies.

PPE analyzed

N95, surgical and cotton masks

Ong et al.88. Ong SWX, Tan YK, Sutjipto S, et al. Absence of contamination of personal protective equipment (PPE) by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Infect Control Hosp Epidemiol. 2020;41(5):614-6. PMID: 32213231; https://doi.org/10.1017/ice.2020.91.
https://doi.org/https://doi.org/10.1017/...
evaluated the front of the goggles and the front of the N95 masks of professionals who cared for 15 patients with COVID-19 in isolation rooms. These were each used during one day of activity and no contamination was found on these materials, thus confirming that prolonged use of N95 masks and goggles with adequate environmental and hand hygiene is a safe option. Arumuru et al.2424. Arumuru V, Pasa J, Samantaray SS. Experimental visualization of sneezing and efficacy of face masks and shields. Phys Fluids (1994). 2020;32(11):115129. PMID: 33244217; https://doi.org/10.1063/5.0030101.
https://doi.org/https://doi.org/10.1063/...
evaluated the effectiveness of homemade cotton masks with three layers, N95 masks, standard three-layer surgical masks and face shields, using a sneeze simulator. They concluded that none of these measures effectively blocked the escape of particles ejected during sneezing. Protective measures effectively reduced leakage and shortened the sneeze range to between 30 and 90 cm. These authors stated that, without a mask, particles from a common sneeze can be projected for approximately 760 cm (25 ft) in almost 22 seconds. The N95 masks completely prevented the particles from leaking forwards, but leakage could still occur sideways and could move up to 60 cm backwards.

Face shields

Three studies on 3D-printed face shields and one study on N95 masks met our inclusion criteria for this investigation. Face shields produced through 3D printing were presented as an easy-to-implement economical alternative that would promote safety for users against infection by COVID-19 aerosols. One important point presented in these articles related to reducing the contamination and dirt of N95 masks, so as to favor longer-duration use and provide additional protection.

Chaturvedi et al.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
evaluated 3D printed face shields in terms of cost-effectiveness, ergonomics, reuse and acceptance by orthopedic surgeons and emergency medical personnel. They reported that there was positive feedback regarding all variables.

On the other hand, Noguera et al.2020. Noguera SV, Espinoza EPS, Côrtes MF, et al. Disinfection of 3D-printed protective face shield during COVID-19 pandemic. Am J Infect Control. 2021;49(4):512-5. PMID: 33080363; https://doi.org/10.1016/j.ajic.2020.10.008.
https://doi.org/https://doi.org/10.1016/...
evaluated low-cost 3D-printed face shields for use by healthcare professionals during their shifts for treating patients with COVID-19. The disinfection protocols used on these shields were tested, and the comfort, visual integrity and viability of the protectors were evaluated by these professionals. These shields were found to be well accepted by the professionals. Chemical disinfection with 70% ethanol, 0.1% sodium hypochlorite and a mixture of quaternary ammonium and H2O2 was effective and did not cause changes to the materials of the face shields. Nonetheless, autoclaving has been shown to cause physical changes to face shields and should not be used.

The study carried out among interventional radiologists by Sapoval et al.2121. Sapoval M, Gaultier AL, Del Giudice C, et al. 3D-printed face protective shield in interventional radiology: Evaluation of an immediate solution in the era of COVID-19 pandemic. Diagn Interv Imaging. 2020;101(6):413-5. PMID: 32354631; https://doi.org/10.1016/j.diii.2020.04.004.
https://doi.org/https://doi.org/10.1016/...
aimed to clinically evaluate face shields printed on a 3D printer with regard to protection against droplets from ­SARS-CoV-2, through 31 interventional procedures. Satisfactory results regarding visual comfort and tolerance were obtained.

Armijo et al.2525. Armijo PR, Markin NW, Nguyen S, et al. 3D printing of face shields to meet the immediate need for PPE in an anesthesiology department during the COVID-19 pandemic. Am J Infect Control. 2021;49(3):302-8. PMID: 32763350; https://doi.org/10.1016/j.ajic.2020.07.037.
https://doi.org/https://doi.org/10.1016/...
aimed to meet the demands of anesthesiologists regarding the safety of masks to protect against COVID-19 infection. They also sought to minimize the contamination and dirt of N95 masks, so as to favor their reuse through an ultraviolet radiation sterilization protocol. Face shields were found to be useful, with low cost, and the decontamination protocol was highly effective against Escherichia coli and Staphylococcus aureus in the tests performed.

Protective goggles

No specific studies on goggles that met the inclusion criteria were identified.

Flexible enclosure with plastic cover or polycarbonate intubation box

A flexible enclosure with a plastic cover or polycarbonate intubation box was used in a study by Smith et al.,2727. Smith CR, Gravenstein N, LeMaster TE, Borde CM, Fahy BG. A Flexible Enclosure to Protect Respiratory Therapists During Aerosol-Generating Procedures. Respir Care. 2020;65(12):1923-32. PMID: 33229369. https://doi.org/10.4187/respcare.08568.
https://doi.org/https://doi.org/10.4187/...
with testing during an endotracheal intubation procedure in an intensive care unit. A simulated patient with COVID-19 was attended by a laryngoscopist, a respiratory therapist who assisted in the intubation and a nurse. Both the PPE used (gloves, apron, shoes and face shields) and the healthcare professionals themselves were evaluated for contamination, by means of fluorescent markers that were sprayed out by an atomizer throughout the procedure. The flexible enclosure for coronavirus was found to contain the fluorescent marker more effectively during endotracheal intubation than PPE alone or the intubation box, based on the exposure of the laryngoscopist and respiratory support therapist.

Plastic curtains

Plastic curtains were tested in a study by Chow et al.2323. Chow VLY, Chan JYW, Ho VWY, et al. Tracheostomy during COVID-19 pandemic-Novel approach. Head Neck. 2020;42(7):1367-73. PMID: 32358855; https://doi.org/10.1002/hed.26234.
https://doi.org/https://doi.org/10.1002/...
during five surgical procedures that involved tracheostomy and head and neck surgery. Droplet contamination was observed on all the plastic sheets that made up the curtain, such that this contamination was highest on the central surface, then on the left-side surface and then on the right. No contamination was seen on the face shields. Thus, this device can minimize transmission of the virus to healthcare professionals.

PPE disinfection and cleaning

Noguera et al.2020. Noguera SV, Espinoza EPS, Côrtes MF, et al. Disinfection of 3D-printed protective face shield during COVID-19 pandemic. Am J Infect Control. 2021;49(4):512-5. PMID: 33080363; https://doi.org/10.1016/j.ajic.2020.10.008.
https://doi.org/https://doi.org/10.1016/...
aimed to evaluate the use of 3D printed face shields for comfort, durability, visual integrity and viability, and ways of disinfecting them. They observed that simple forms of disinfection, used conventionally, were safe and effective, except for autoclaving, which could cause significant damage to some materials used in making face shields.

Armijo et al.2525. Armijo PR, Markin NW, Nguyen S, et al. 3D printing of face shields to meet the immediate need for PPE in an anesthesiology department during the COVID-19 pandemic. Am J Infect Control. 2021;49(3):302-8. PMID: 32763350; https://doi.org/10.1016/j.ajic.2020.07.037.
https://doi.org/https://doi.org/10.1016/...
aimed to provide additional protection for healthcare professionals, at low cost, that would reduce the potential contamination of N95 masks, thereby favoring longer duration of use with easy decontamination. They concluded that the use of N95 with face shields was useful and that the protocol for decontamination with a diluted bleach solution allowed penetration into any of the pores generated in the 3D printing process of the face shield, such that the decontamination process was highly effective.

Saini et al.2626. Saini V, Sikri K, Batra SD, Kalra P, Gautam K. Development of a highly effective low-cost vaporized hydrogen peroxide-based method for disinfection of personal protective equipment for their selective reuse during pandemics. Gut Pathog. 2020;12:29. PMID: 32572338; https://doi.org/10.1186/s13099-020-00367-4.
https://doi.org/https://doi.org/10.1186/...
aimed to evaluate biological indicators as positive sterilization controls and to develop a method using vaporized hydrogen peroxide. They demonstrated that there was no impairment of the materials and no alteration of comfort perceived by the user.

Fischer et al.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
aimed to compare methods for decontamination of N95 masks using ultraviolet light (260-285 nm), dry heat at 70 °C, 70% alcohol and vaporization with hydrogen peroxide. Vaporization with hydrogen peroxide showed the best results concerning SARS-CoV-2 and preservation of the integrity of N95 masks. Ultraviolet light eliminated SARS-CoV-2 more slowly and preserved the function of the N95 mask almost as well as vaporization with hydrogen peroxide. Both of these techniques allowed N95 masks to be reused three times.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
Dry heat at 70 °C eliminated the virus with a speed similar to ultraviolet light, and was likely to maintain acceptable adjustment values for one or two decontaminations.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
Decontamination with 70% alcohol reduced the integrity of N95 masks and was not recommended.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...

Satisfaction of healthcare professionals in relation to PPE

Chaturvedi et al.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
aimed to analyze the effectiveness of face shields made in a 3D printer that were used by orthopedists and emergency medical professionals. These professionals considered them to be satisfactory for use.

Sapoval et al.2121. Sapoval M, Gaultier AL, Del Giudice C, et al. 3D-printed face protective shield in interventional radiology: Evaluation of an immediate solution in the era of COVID-19 pandemic. Diagn Interv Imaging. 2020;101(6):413-5. PMID: 32354631; https://doi.org/10.1016/j.diii.2020.04.004.
https://doi.org/https://doi.org/10.1016/...
aimed to evaluate the risk factors for COVID-19 among interventional anesthesiologists who used 3D-printed face shields during routine procedures in hospitals. It was concluded that 3D-printed face shields were well-accepted by anesthesiologists and fulfilled the proposed objectives.

DISCUSSION

The main contribution of this review was to synthesize the best available evidence about the use, reuse and disinfection of PPE as a non-pharmacological intervention, used in association with other measures for preventing contamination by ­COVID-19, such as cough etiquette (a common cough can travel at least 1.5-3 meters)2424. Arumuru V, Pasa J, Samantaray SS. Experimental visualization of sneezing and efficacy of face masks and shields. Phys Fluids (1994). 2020;32(11):115129. PMID: 33244217; https://doi.org/10.1063/5.0030101.
https://doi.org/https://doi.org/10.1063/...
and hand hygiene, for healthcare professionals.

The main point for management of COVID-19 infection is to prevent in-hospital infection among healthcare professionals.2828. Hiramatsu M, Nishio N, Ozaki M, et al. Anesthetic and surgical management of tracheostomy in a patient with COVID-19. Auris Nasus Larynx. 2020;47(3):472-6. PMID: 32345515; https://doi.org/10.1016/j.anl.2020.04.002.
https://doi.org/https://doi.org/10.1016/...
Coronavirus can spread through aerosols, droplets and contact contamination.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
A droplet of 10 μm in diameter may persist suspended in the air for about 50 seconds when sneezing.2424. Arumuru V, Pasa J, Samantaray SS. Experimental visualization of sneezing and efficacy of face masks and shields. Phys Fluids (1994). 2020;32(11):115129. PMID: 33244217; https://doi.org/10.1063/5.0030101.
https://doi.org/https://doi.org/10.1063/...
Since the half-life of the virus is approximately 6-7 hours, it is unlikely that there will be a viable amount of virus in the mask for three full days.2929. van Doremalen N, Bushmaker T, Morris DH, et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. N Engl J Med. 2020;382(16):1564-7. PMID: 32182409; https://doi.org/10.1056/NEJMc2004973.
https://doi.org/https://doi.org/10.1056/...
van Doremalen et al.2929. van Doremalen N, Bushmaker T, Morris DH, et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. N Engl J Med. 2020;382(16):1564-7. PMID: 32182409; https://doi.org/10.1056/NEJMc2004973.
https://doi.org/https://doi.org/10.1056/...
analyzed the survival of SARS-CoV-2 with 40% humidity at temperatures of 70-73 °F (21-22 °C), and concluded that it could survive as follows:

  • Up to 3 hours after aerosolization, with an average half-life of 1.1 to 1.2 hours.

  • Up to 4 hours on copper, with an average half-life of 1.1 to 1.2 hours.

  • Up to 24 hours on cardboard, with an average half-life of approximately 3.5 hours.

  • Up to 2 days on stainless steel, with an average half-life of 5.6 hours.

  • Up to 3 days on plastic, with an average half-life of 6.8 hours.

Face shields have been classified as a form of PPE that protects the facial area and related mucous membranes (ear, nose and mouth) from splashes of body fluids.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
,3030. Celik HK, Kose O, Ulmeanu M-E, et al. Design and Additive Manufacturing of Medical Face Shield for Healthcare Workers Battling Coronavirus (COVID-19). Int J Bioprint. 2020;6(4):286. PMID: 33088997; https://doi.org/10.18063/ijb.v6i4.286.
https://doi.org/https://doi.org/10.18063...
Among the four types of PPE for the facial region, namely, face shields, face shields with N95 respirator, surgical masks with eye protector and safety glasses with N95 respirator, face shields with N95 respirator are the most effective.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
The association of a face shield with N95 respirator and a flexible enclosure with a plastic cover or polycarbonate intubation box, as demonstrated by Smith et al.,2727. Smith CR, Gravenstein N, LeMaster TE, Borde CM, Fahy BG. A Flexible Enclosure to Protect Respiratory Therapists During Aerosol-Generating Procedures. Respir Care. 2020;65(12):1923-32. PMID: 33229369. https://doi.org/10.4187/respcare.08568.
https://doi.org/https://doi.org/10.4187/...
along with the plastic curtain that was used in the study by Chow et al.,2727. Smith CR, Gravenstein N, LeMaster TE, Borde CM, Fahy BG. A Flexible Enclosure to Protect Respiratory Therapists During Aerosol-Generating Procedures. Respir Care. 2020;65(12):1923-32. PMID: 33229369. https://doi.org/10.4187/respcare.08568.
https://doi.org/https://doi.org/10.4187/...
may be of special importance for protection of healthcare professionals during procedures such as orotracheal intubation and procedures involving tracheostomy.

Use of face shields can substantially reduce healthcare professionals’ short-term exposure to larger particles of infectious aerosols and can reduce the contamination of their respirators.1111. Lindsley WG, Noti JD, Blachere FM, Szalajda JV, Beezhold DH. Efficacy of face shields against cough aerosol droplets from a cough simulator. J Occup Environ Hyg. 2014;11(8):509-18. PMID: 24467190; https://doi.org/10.1080/15459624.2013.877591.
https://doi.org/https://doi.org/10.1080/...
,3131. Li IW, Fan JK, Lai AC, Lo CM. Home-made masks with filtration efficiency for nano-aerosols for community mitigation of COVID-19 pandemic. Public Health. 2020;188:42-50. PMID: 33075669; https://doi.org/10.1016/j.puhe.2020.08.018.
https://doi.org/https://doi.org/10.1016/...
,3232. Khan MM, Parab SR. Safety guidelines for sterility of face shields during COVID 19 pandemic. Indian J Otolaryngol Head Neck Surg. 2020:73(1):1-2. PMID: 32355658; https://doi.org/10.1007/s12070-020-01865-2.
https://doi.org/https://doi.org/10.1007/...
They are less effective against smaller particles, which can remain in the air for long periods and easily flow around a face mask, for inhalation.1111. Lindsley WG, Noti JD, Blachere FM, Szalajda JV, Beezhold DH. Efficacy of face shields against cough aerosol droplets from a cough simulator. J Occup Environ Hyg. 2014;11(8):509-18. PMID: 24467190; https://doi.org/10.1080/15459624.2013.877591.
https://doi.org/https://doi.org/10.1080/...
Thus, face shields can provide a useful complement to respiratory protection for workers who care for patients with respiratory infections but cannot be used as a substitute for respiratory protection.1111. Lindsley WG, Noti JD, Blachere FM, Szalajda JV, Beezhold DH. Efficacy of face shields against cough aerosol droplets from a cough simulator. J Occup Environ Hyg. 2014;11(8):509-18. PMID: 24467190; https://doi.org/10.1080/15459624.2013.877591.
https://doi.org/https://doi.org/10.1080/...
,3232. Khan MM, Parab SR. Safety guidelines for sterility of face shields during COVID 19 pandemic. Indian J Otolaryngol Head Neck Surg. 2020:73(1):1-2. PMID: 32355658; https://doi.org/10.1007/s12070-020-01865-2.
https://doi.org/https://doi.org/10.1007/...
Although face shields are bulkier than goggles or safety glasses, they offer the advantage of protecting the entire face from contamination.1111. Lindsley WG, Noti JD, Blachere FM, Szalajda JV, Beezhold DH. Efficacy of face shields against cough aerosol droplets from a cough simulator. J Occup Environ Hyg. 2014;11(8):509-18. PMID: 24467190; https://doi.org/10.1080/15459624.2013.877591.
https://doi.org/https://doi.org/10.1080/...
,3030. Celik HK, Kose O, Ulmeanu M-E, et al. Design and Additive Manufacturing of Medical Face Shield for Healthcare Workers Battling Coronavirus (COVID-19). Int J Bioprint. 2020;6(4):286. PMID: 33088997; https://doi.org/10.18063/ijb.v6i4.286.
https://doi.org/https://doi.org/10.18063...
Some professionals may also feel more comfortable with face shields or may find that they fit better than glasses or respirators.1111. Lindsley WG, Noti JD, Blachere FM, Szalajda JV, Beezhold DH. Efficacy of face shields against cough aerosol droplets from a cough simulator. J Occup Environ Hyg. 2014;11(8):509-18. PMID: 24467190; https://doi.org/10.1080/15459624.2013.877591.
https://doi.org/https://doi.org/10.1080/...
,3030. Celik HK, Kose O, Ulmeanu M-E, et al. Design and Additive Manufacturing of Medical Face Shield for Healthcare Workers Battling Coronavirus (COVID-19). Int J Bioprint. 2020;6(4):286. PMID: 33088997; https://doi.org/10.18063/ijb.v6i4.286.
https://doi.org/https://doi.org/10.18063...

During the pandemic, cheaper solutions have emerged that can be developed locally, such as face shields, masks, etc.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
These solutions are being widely propagated in urban areas with large-scale 3D printing facilities.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
In the situation of lockdowns to which many regions have been subjected, domestic production becomes crucial for obtaining the best functional results regarding production of PPE.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
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Production of face shields is simple: they consist of three parts, i.e. the frame, an elastic cord for attachment and a transparent plastic visor.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
,3232. Khan MM, Parab SR. Safety guidelines for sterility of face shields during COVID 19 pandemic. Indian J Otolaryngol Head Neck Surg. 2020:73(1):1-2. PMID: 32355658; https://doi.org/10.1007/s12070-020-01865-2.
https://doi.org/https://doi.org/10.1007/...
When produced using a 3D printer, the total cost of one face shield is approximately one dollar, which makes it an economical device, considering its reusability.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
,3232. Khan MM, Parab SR. Safety guidelines for sterility of face shields during COVID 19 pandemic. Indian J Otolaryngol Head Neck Surg. 2020:73(1):1-2. PMID: 32355658; https://doi.org/10.1007/s12070-020-01865-2.
https://doi.org/https://doi.org/10.1007/...

Before disinfecting face shields, they need to be disassembled.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
Polyvinyl chloride (PVC) film visors should be discarded after use and replaced for the next cycle of use.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
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The disinfection procedures to be followed are as per the recommendations of the CDC, using standard disinfection solutions such as isopropyl alcohol or sodium hypochlorite, and subsequently performing proper hand hygiene.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
It is advisable to discard the paper clips or band after one cycle of use. Nonetheless, in situations that require reuse, they can be disinfected using a hospital disinfectant solution that has been registered with the Environmental Protection Agency (EPA).77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
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This information is decisive when thinking about mask reuse and the cost of masks. In March 2020, the U.S. Department of Health and Human Services announced that its national inventory strategy, i.e. the emergency stock of medicines and medical supplies, contained approximately 42 million masks, totaling both surgical and N95 masks.1414. Bartoszko JJ, Farooqi MAM, Alhazzani W, Loeb M. Medical masks vs N95 respirators for preventing COVID-19 in healthcare workers: A systematic review and meta-analysis of randomized trials. Influenza Other Respi Viruses. 2020;14(4):365-73. PMID: 32246890; https://doi.org/10.1111/irv.12745.
https://doi.org/https://doi.org/10.1111/...
,3333. Berenson T. States need medical supplies to fight coronavirus. Canthe National Stockpile keep up with the demand? Published March 10, 2020. Available from: Available from: https://time.com/5800200/strategic-national-stockpile-coronavirus/ . Accessed in 2021 (Apr 30).
https://time.com/5800200/strategic-natio...
This is equivalent to 1% of the estimated amount needed by United States healthcare professionals in a pandemic scenario (42 million stored compared with the estimated 3.5 billion needed).1414. Bartoszko JJ, Farooqi MAM, Alhazzani W, Loeb M. Medical masks vs N95 respirators for preventing COVID-19 in healthcare workers: A systematic review and meta-analysis of randomized trials. Influenza Other Respi Viruses. 2020;14(4):365-73. PMID: 32246890; https://doi.org/10.1111/irv.12745.
https://doi.org/https://doi.org/10.1111/...
,3333. Berenson T. States need medical supplies to fight coronavirus. Canthe National Stockpile keep up with the demand? Published March 10, 2020. Available from: Available from: https://time.com/5800200/strategic-national-stockpile-coronavirus/ . Accessed in 2021 (Apr 30).
https://time.com/5800200/strategic-natio...
In addition, use of face shields reduces mask contamination, when they are used together, thus extending their useful life.2525. Armijo PR, Markin NW, Nguyen S, et al. 3D printing of face shields to meet the immediate need for PPE in an anesthesiology department during the COVID-19 pandemic. Am J Infect Control. 2021;49(3):302-8. PMID: 32763350; https://doi.org/10.1016/j.ajic.2020.07.037.
https://doi.org/https://doi.org/10.1016/...

Although face shields do not offer absolute protection against contamination, they significantly decrease the chances of contracting the coronavirus.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
One of the main problems with face shields and PPE hoods is the fogging of the visor, which impairs users’ abilities during procedures and surgeries.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...
Discomfort due to lack of adequate ventilation is also a considerable concern.77. Chaturvedi S, Gupta A, Krishnan SV, Bhat AK. Design, usage and review of a cost effective and innovative face shield in a tertiary care teaching hospital during COVID-19 pandemic. J Orthop. 2020;24(21):331-6. PMID: 32753794; https://doi.org/10.1016/j.jor.2020.07.003.
https://doi.org/https://doi.org/10.1016/...

Li et al. analyzed masks after disinfection with 75% alcohol or soap and water at 60 °C and noted that the structure of the medical masks was damaged after treatment with these substances.3131. Li IW, Fan JK, Lai AC, Lo CM. Home-made masks with filtration efficiency for nano-aerosols for community mitigation of COVID-19 pandemic. Public Health. 2020;188:42-50. PMID: 33075669; https://doi.org/10.1016/j.puhe.2020.08.018.
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Use of water and soap or alcohol significantly reduces the filtering efficiency of N95 masks (54% and 67%, respectively).3434. Juang PSC, Tsai P. N95 respirator cleaning and reuse methods proposed by the inventor of the N95 mask material. J Emerg Med. 2020;58(5):817-20. PMID: 32389433; https://doi.org/10.1016/j.jemermed.2020.04.036.
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Treating these masks with gamma radiation is also not recommended.3434. Juang PSC, Tsai P. N95 respirator cleaning and reuse methods proposed by the inventor of the N95 mask material. J Emerg Med. 2020;58(5):817-20. PMID: 32389433; https://doi.org/10.1016/j.jemermed.2020.04.036.
https://doi.org/https://doi.org/10.1016/...
Autoclaving is not indicated for disinfection of face shields printed on 3D printers since it can cause significant damage to some materials used in their manufacture.2020. Noguera SV, Espinoza EPS, Côrtes MF, et al. Disinfection of 3D-printed protective face shield during COVID-19 pandemic. Am J Infect Control. 2021;49(4):512-5. PMID: 33080363; https://doi.org/10.1016/j.ajic.2020.10.008.
https://doi.org/https://doi.org/10.1016/...
Chemical disinfection with 70% ethanol, 0.1% sodium hypochlorite and a mixture of quaternary ammonium and H2O2 is indicated.2020. Noguera SV, Espinoza EPS, Côrtes MF, et al. Disinfection of 3D-printed protective face shield during COVID-19 pandemic. Am J Infect Control. 2021;49(4):512-5. PMID: 33080363; https://doi.org/10.1016/j.ajic.2020.10.008.
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Decontamination with diluted bleach solution is also an option.2525. Armijo PR, Markin NW, Nguyen S, et al. 3D printing of face shields to meet the immediate need for PPE in an anesthesiology department during the COVID-19 pandemic. Am J Infect Control. 2021;49(3):302-8. PMID: 32763350; https://doi.org/10.1016/j.ajic.2020.07.037.
https://doi.org/https://doi.org/10.1016/...
Moreover, diluted bleach solution is useful for disinfection from some bacteria, such as Staphylococcus aureus.2525. Armijo PR, Markin NW, Nguyen S, et al. 3D printing of face shields to meet the immediate need for PPE in an anesthesiology department during the COVID-19 pandemic. Am J Infect Control. 2021;49(3):302-8. PMID: 32763350; https://doi.org/10.1016/j.ajic.2020.07.037.
https://doi.org/https://doi.org/10.1016/...

SARS-CoV-2 has been found to be highly stable at 4 °C but sensitive to heat.3535. Chin AWH, Chu JTS, Perera MRA, et al. Stability of SARS-CoV-2 in different environmental conditions. Lancet Microbe. 2020;1(1):e10. PMID: 32835322; https://doi.org/10.1016/S2666-5247(20)30003-3.
https://doi.org/https://doi.org/10.1016/...
According to the inventor of the N95 mask material, Dr. Peter Tsai, this material can be heated for 60 minutes, steamed at 125 °C for five minutes or boiled for five minutes, and then air-dried.3434. Juang PSC, Tsai P. N95 respirator cleaning and reuse methods proposed by the inventor of the N95 mask material. J Emerg Med. 2020;58(5):817-20. PMID: 32389433; https://doi.org/10.1016/j.jemermed.2020.04.036.
https://doi.org/https://doi.org/10.1016/...
Most viruses are killed in less than two minutes when the water temperature reaches 70 °C (158 °F).3434. Juang PSC, Tsai P. N95 respirator cleaning and reuse methods proposed by the inventor of the N95 mask material. J Emerg Med. 2020;58(5):817-20. PMID: 32389433; https://doi.org/10.1016/j.jemermed.2020.04.036.
https://doi.org/https://doi.org/10.1016/...
,3636. World Health Organization. Boil water. Geneva: World Health Organization; 2015. Available from: Available from: https://apps.who.int/iris/handle/10665/155821 . Accessed in 2021 (Apr 30).
https://apps.who.int/iris/handle/10665/1...
The rubber band must not be immersed in boiling water.3434. Juang PSC, Tsai P. N95 respirator cleaning and reuse methods proposed by the inventor of the N95 mask material. J Emerg Med. 2020;58(5):817-20. PMID: 32389433; https://doi.org/10.1016/j.jemermed.2020.04.036.
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Through these methods, 92.4% and 91.7%-98.5% of mask filtration efficiency is retained and the criteria required by the Food and Drug Administration (FDA) and the CDC are met.3434. Juang PSC, Tsai P. N95 respirator cleaning and reuse methods proposed by the inventor of the N95 mask material. J Emerg Med. 2020;58(5):817-20. PMID: 32389433; https://doi.org/10.1016/j.jemermed.2020.04.036.
https://doi.org/https://doi.org/10.1016/...
Nevertheless, if these methods are performed for more than five minutes, the efficiency of the filtration will drop further.3434. Juang PSC, Tsai P. N95 respirator cleaning and reuse methods proposed by the inventor of the N95 mask material. J Emerg Med. 2020;58(5):817-20. PMID: 32389433; https://doi.org/10.1016/j.jemermed.2020.04.036.
https://doi.org/https://doi.org/10.1016/...

Use of hydrogen peroxide was helpful in disinfecting PPE without damaging its material.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
,2626. Saini V, Sikri K, Batra SD, Kalra P, Gautam K. Development of a highly effective low-cost vaporized hydrogen peroxide-based method for disinfection of personal protective equipment for their selective reuse during pandemics. Gut Pathog. 2020;12:29. PMID: 32572338; https://doi.org/10.1186/s13099-020-00367-4.
https://doi.org/https://doi.org/10.1186/...
Decontamination through vaporization with hydrogen peroxide showed the best results concerning the speed of inactivation of SARS-CoV-2 and preservation of the integrity of N95 masks.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
In the sequence, ultraviolet light eliminated SARS-CoV-2 more slowly and preserved the function of the N95 masks almost as well as vaporization with hydrogen peroxide, thus allowing the masks to be reused up to three times.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
Although dry heat at 70 °C eliminate the virus at a speed similar to that of ultraviolet light, it damages the masks and thus only allows reuse twice.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
Seventy percent alcohol impairs the integrity of N95 masks, and decontamination with this substance is not indicated.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...
,3737. Viscusi DJ, Bergman MS, Eimer BC, Shaffer RE. Evaluation of five decontamination methods for filtering facepiece respirators. Ann Occup Hyg. 2009;53(8):815-27. PMID: 19805391; https://doi.org/10.1093/annhyg/mep070.
https://doi.org/https://doi.org/10.1093/...

The ideal would be to use an N95 mask for one day and only use it again on the fifth day, which would therefore require at least four masks.3434. Juang PSC, Tsai P. N95 respirator cleaning and reuse methods proposed by the inventor of the N95 mask material. J Emerg Med. 2020;58(5):817-20. PMID: 32389433; https://doi.org/10.1016/j.jemermed.2020.04.036.
https://doi.org/https://doi.org/10.1016/...
All copies of SARS-CoV-2 on the mask will be dead within three days even if no decontamination is performed.2929. van Doremalen N, Bushmaker T, Morris DH, et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. N Engl J Med. 2020;382(16):1564-7. PMID: 32182409; https://doi.org/10.1056/NEJMc2004973.
https://doi.org/https://doi.org/10.1056/...
,3434. Juang PSC, Tsai P. N95 respirator cleaning and reuse methods proposed by the inventor of the N95 mask material. J Emerg Med. 2020;58(5):817-20. PMID: 32389433; https://doi.org/10.1016/j.jemermed.2020.04.036.
https://doi.org/https://doi.org/10.1016/...

Although quaternary ammonium or bleach can also be used to disinfect gloves,1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...
there is no evidence that they have any action on COVID-19. It should also be noted that there is little evidence that using two gloves on each hand as part of full-body PPE can reduce the risk of contamination and reduce the viral load on the hands without constant change of the gloves.1010. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev. 2020;5:CD011621. PMID: 32412096; https://doi/10.1002/14651858.CD011621.pub5.
https://doi.org/https://doi/10.1002/1465...

None of the articles identified showed the ideal length of time for using the masks, or how to safely store them for reuse. However, the need to follow the recommendations of the company responsible for the product and those of the hospital’s infection control commission were indicated.2222. Fischer RJ, Morris DH, van Doremalen N, et al. Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus. Emerging Infect Dis. 2020;26(9). PMID: 32491983; https://doi.org/10.3201/eid2609.201524.
https://doi.org/https://doi.org/10.3201/...

Implications for practice

The implications for practice of this review are that combined use of a face shield with a N95 mask among healthcare professionals may increase these professionals’ protection. This would enable them to have a lower rate of infection and would thus reduce the pressure on the healthcare system.

Emphasis should also be given to the possible disinfection of these materials with 70% ethanol, 0.1% sodium hypochlorite, bleaches and a mixture of quaternary ammonium with H2O2. Disinfection, with the possibility of reuse, reduces the demand for these PPE materials, which may reduce the cost to institutions.

Disinfection of N95 masks by means of vaporization using hydrogen peroxide or ultraviolet light made it possible to reuse these masks three times, while use of dry heat at 70 °C allowed reuse twice. Decontamination with 70% alcohol would reduce the filtration efficiency of N95 masks and is not recommended. The main findings from the systematic review are summarized in Table 2.

Research implications

There is a need to assess the durability of PPE and how to store it properly after use and disinfection. It is also necessary to evaluate disposable gloves and aprons, in order to reduce the demand for these items, given the large number of exchanges necessary during the work periods of healthcare professionals and their increasing market price, which is increasing the costs of professionals, institutions and governments.

We identified that there is a need for randomized controlled studies and observational studies with adequate designs, in order to better identify the risk factors, effectiveness, safety and cost of preventive measures for healthcare professionals who are faced with the challenge of COVID-19.

CONCLUSION

The studies identified so far provide low levels of evidence but consistently demonstrate that N95 masks, surgical masks and face shields, both those industrially manufactured and those produced through lower-cost 3D printers, are meaningful devices that act as a barrier to droplets and enable protection for healthcare professionals against COVID-19 infection. However, additional care regarding the length of time of use, disinfection and reuse is needed, along with hand hygiene and care regarding placement and removal of these devices. Combined use of a face shield and a N95 mask proved to be superior to separate use of each device or associations between face shields and surgical or cloth masks.

Auxiliary devices, such as flexible enclosures for coronavirus and plastic curtains, may be an additional alternative for protecting professionals who are directly involved in procedures with a higher risk of contamination, such as orotracheal intubation and tracheostomy. Some products are useful for disinfecting PPE, such as 70% ethanol, 0.1% sodium hypochlorite and a mixture of quaternary ammonium and hydrogen peroxide. Ultraviolet light and dry heat at 70 °C can be used to decontaminate N95 masks, while it needs to be borne in mind that dry heat at 70 °C reduces the integrity of N95 masks more dramatically.

REFERENCES

  • 1
    Evidence-Based Health Department, Universidade Federal de São Paulo (UNIFESP), São Paulo (SP), Brazil

  • Sources of funding: This project was financed by CNPQ MCTIC/CNPq/FNDCT/MS/SCTIE/Decit number 07/2020 - Research to face COVID-19, its consequences and other severe acute respiratory syndromes

Publication Dates

  • Publication in this collection
    17 Dec 2021
  • Date of issue
    Jan-Feb 2022

History

  • Reviewed
    17 Feb 2021
  • Received
    30 Apr 2021
  • Accepted
    18 May 2021
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