Coronavirus versus 70% Alcohol: Comments and Some Fundamental Definitions

Abstract

The new coronavirus pandemic (COVID-19) is a global problem that is having severe impacts on health systems worldwide. One particular characteristic of this virus is its high transmission rate, which has led to a high demand for personal care materials such as masks, gloves, and alcohol for asepsis. Seventy percent is the ideal concentration for the ethanol used in hand sanitizers; however, this concentration can be expressed in different ways, and, consequently, the different solutions will have different antiseptic activity. In this manuscript we comment on some characteristics of alcohol-based preparations and the different ways of expressing the concentrations.

Keywords:
SARS-CoV-2; COVID-19; 70% ethanol

INTRODUCTION

SARS-CoV-2 is a variant of the coronavirus family, and it is responsible for the COVID-19 disease. Due to it being another type of coronavirus, SARS-CoV-2 can infect humans (WHO, 2020a). On March 11, 2020, the World Health Organization (WHO) declared COVID-19 a pandemic (WHO, 2020b; WHO, 2020c). Italy was one of the most affected countries, due to its large number of elderly people, who account for 22.1% of the population (CIA, 2020). The elderly and people with chronic diseases (e.g., immunosuppressed people, and those with heart and cardio-respiratory problems, diabetes, and autoimmune diseases) are the groups most at risk of being affected by COVID-19 (WHO, 2020a) - a situation that alarmed public sectors and the general population as well. The recommendations adopted by both the Brazilian Ministry of Health Care and control agencies were the same as those suggested by the WHO, including the use of 70% alcohol gel in asepsis and hand hygiene (WHO, 2020a; Brasil, Ministério da Saúde, 2020).

TECHNICAL COMMENTS

At this critical moment, the veracity of information and appropriate interpretations are fundamental for ensuring quick control of COVID-19 propagation; however, there is inaccurate information and uncertainties surrounding the ethanol concentration in antiseptic alternatives. Different concentration forms, expressed in percentage, can be found in the literature or in recommendations from authorities; for example, 70% volume per volume (v/v) (Kampf, 2018), weight per volume (w/v) (Andrade et al., 2007), or weight per weight (w/w) (Kampf, 2018; Venturelli et al., 2009). On the homepage of the Brazilian Federal Chemistry Council (Conselho Federal de Química - CFQ), there are two official notes about coronavirus and use of 70% ethanol, each one with a different concentration: 70% v/v (CFQ, 2020a) and 70° INPM (CFQ, 2020b). Thus, given the recurring divergence in the information, some clarifications are necessary. The ethanol concentration presented as degrees Gay-Lussac (°GL) is the same as v/v; whereas degrees INPM (Instituto Nacional de Pesos e Medidas - the Brazilian National Institute of Weights and Measurements) is equivalent to w/w (Brasil, Ministério da Saúde, 2012). Another important piece of information is the convention that a percentage concentration is equivalent to the w/w concentration. Thus, when ethanol concentration is given as 70%, this means that the ethanol’s weight corresponds to 70% of the solution’s total weight (i.e., it is different to 70% v/v).

In general, formulations of 60 to 95% alcohol (e.g., ethanol, isopropanol, etc.) are referred to in the literature, and these concentrations have been effective against most microorganisms (Kampf, 2018; Harrington and Walker, 1903; Boyce and Pittet, 2002; Price, 1939; Kampf et al., 2020). In terms of general use, 70% ethanol is the most effective antiseptic form available for purchase. The 70% is correctly expressed as percent by weight (w/w) - the solution is exact and invariable, and so the weight is not affected by variables such as temperature, specific gravity, or intermolecular interactions (Price, 1938). When prepared at 15 °C and 25 °C, 70% ethanol (v/v) is equivalent to 62.4% (w/w) and 59.2% (w/w), respectively. This means that 70% ethanol (v/v) solution does not have a sufficient amount of ethanol to ensure the greatest (70%, w/w) antimicrobial activity (Boyce and Pittet, 2002; Price, 1938). To obtain a solution with a final concentration of 70% (w/w), it would be necessary to use 76.8 mL of absolute ethanol for each 100 mL of solution at the v/v ratio.

These discrepancies in the standardization of concentration expressions can lead to mistakes in the final concentrations, which leads to a reduction in the efficiency (e.g. due to the increased demand for contact time) of ethanol solutions or gel (Boyce and Pittet, 2002; Salvage et al., 2014). At a time of global pandemic, all the care possible in preventive action can assist in containing the spread of viruses. For the reasons presented, the purpose of these comments is to alert specialized health agencies and the global population in general about the correct way to express and interpret ethanol concentrations associated with asepsis and hand hygiene.

REFERENCES

• Andrade D, Beraldo CC, Watanabe E, Oliveira BA, Ito IY. Atividade antimicrobiana in vitro do álcool gel a 70% frente às bactérias hospitalares e da comunidade. Medicina (Ribeirão Preto. Online). 2007;40(2):250-254.
• Boyce JM, Pittet D. Guideline for Hand Hygiene in Health-Care Settings: Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/ SHEA/APIC/IDSA Hand Hygiene Task Force. Infect Control Hosp Epidemiol. 2002;23(S12):S3-S40.
• Brasil. Ministério da Saúde. Agência Nacional de Vigilância Sanitária. Formulário Nacional da Farmacopéia Brasileira, 2nd ed. Brasília: Anvisa; 2012. 224 p.
• Brasil. Ministério da Saúde. O que é o Coronavirus? (COVID-19). [citad 2020 Mar 16]. Available from: Available from: https://www.saude.gov.br/o-ministro/928-saude-de-a-a-z/coronavirus
  » https://www.saude.gov.br/o-ministro/928-saude-de-a-a-z/coronavirus
• CIA. Central Intelligence Agency. [ citad 2020 Mar 16]. Available from: Available from: https://www.cia.gov/library/publications/the-world-factbook/geos/it.html
  » https://www.cia.gov/library/publications/the-world-factbook/geos/it.html
• Conselho Federal de Química. Nota Oficial - Propriedades do álcool em gel. [citad 2020 Mar 15]. Available from: Available from: cfq.org.br/noticia/nota-oficial-propriedades-do-alcool-gel
  » cfq.org.br/noticia/nota-oficial-propriedades-do-alcool-gel
• Conselho Federal de Química. Nota Oficial - Medidas de prevenção ao contágio pelo coronavirus. [ citad 2020 Mar 15]. Available from: Available from: cfq.org.br/noticia/nota-oficial-medidas-de-prevencao-ao-contagio-pelo-coronavirus
  » cfq.org.br/noticia/nota-oficial-medidas-de-prevencao-ao-contagio-pelo-coronavirus
• Harrington C, Walker H. The germicidal action of alcohol. Boston Med Surg J. 1903;148:548-552.
• Kampf G. Efficacy of ethanol against viruses in hand disinfection. J Hosp Infect. 2018;98(4):331-338.
• Kampf G, Todt D, Pfaender S, Steinmann E. Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents. JHosp Infect. 2020;104(3):246-251.
• Price PB. New studies in surgical bacteriology and surgical technic: with special reference to disinfection of the skin. JAMA. 1938;111(22):1993-1996.
• Price PB. Ethyl alcohol as a germicide. Arch Surg. 1939;38(3):528-542.
• Salvage R, Hull CM, Kelly DE, Kelly SL. Use of 70% alcohol for the routine removal of microbial hard surface bioburden in life science cleanrooms. Future Microbiol. 2014;9(10):1123-1130.
• Venturelli AC, Torres FC, Almeida-Pedrin RR, Almeida RR, Almeida MR, Ferreira FPC. Avaliação microbiológica da contaminação residual em diferentes tipos de alicates ortodônticos após desinfecção com álcool 70%. Rev Dent Press Ortod Ortop Facial. 2009;14(4):43-52.
• WHO. World Health Organization. Q&A on coronaviruses (COVID-19). [citad 2020a Mar 16]. Available from: Available from: https://www.who.int/news-room/q-a-detail/q-a-coronaviruses
  » https://www.who.int/news-room/q-a-detail/q-a-coronaviruses
• WHO. World Health Organization. WHO Director-General’s opening remarks at the media briefing on COVID-19 - 11 March 2020. [citad 2020b Mar 16]. Available from: Available from: https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---11-march-2020
  » https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---11-march-2020
• WHO. World Health Organization - Regional Office for Europe. WHO announces COVID-19 outbreak a pandemic. [citad 2020c Mar 16]. Available from: Available from: http://www.euro.who.int/en/health-topics/health-emergencies/coronavirus-covid-19/news/news/2020/3/who-announces-covid-19-outbreak-a-pandemic
  » http://www.euro.who.int/en/health-topics/health-emergencies/coronavirus-covid-19/news/news/2020/3/who-announces-covid-19-outbreak-a-pandemic

Publication Dates

• Publication in this collection
  14 Nov 2022
• Date of issue
  2022

History

• Received
  29 Apr 2020
• Accepted
  30 July 2020