Uses and limits of the clinical laboratory in the COVID-19 pandemic: a didactic review

Araujo, Fernando Antonio Glasner da Rocha

doi:10.1590/1806-9282.66.12.1718

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Review Article • Rev. Assoc. Med. Bras. 66 (12) • Dec 2020 • https://doi.org/10.1590/1806-9282.66.12.1718 copy

Uses and limits of the clinical laboratory in the COVID-19 pandemic: a didactic review

Authorship SCIMAGO INSTITUTIONS RANKINGS

SUMMARY

The world is currently experiencing an unprecedented pandemic of a new disease, the coronavirus disease (COVID-19), which has unusual clinical and immunological presentations. This is especially true regarding the choice and interpretation of laboratory test results. In this review, we have provided didactic information for physicians on the current concepts and practical guidance regarding COVID-19.

KEYWORDS:
Severe acute respiratory syndrome - coronavirus 2; COVID-19; clinical pathology; clinical diagnosis; laboratory

Time	False-negative results
4 days prior to symptom onset	100%
1 day after symptom onset	67%
3 days after symptom onset	20%
4 days after symptom onset	21%
16 days after symptom onset	66%

Collection site	Sensitivity
Bronchoalveolar lavage	93%
Sputum	72%
Nasopharynx	63%
Oropharynx	32%

Pre-test probability	Post-test probability of 1 negative result	Post-test probability of 2 negative results	Post-test probability of 1 positive result
5%	1.6%	0.5%	42%
15%	5%	2%	71%
25%	10%	3%	82%
50%	24%	9%	93%
75%	49%	23%	98%
90%	74%	47%	99%

1^st author	Technique	IgG
		Yes	No	%
Gao	CLIA, ELISA, GICA	14	0	100%
Jiang	Proteome microarray	29	0	100%
Yong	GICA	35	3	92%
Liu	In-house kit	131	2	98%
Long	MCLIA	285	0	100%
Lou	ELISA, LFIA, CMIA	75	5	94%
Pan	ICG strip	65	2	97%
To	EIA	16	0	100%
Zhao	ELISA	112	61	65%
TOTAL	TOTAL	762	73	91%

Patient clinical and epidemiological	Reason for test	First-choice test	What to do if the result is negative
Asymptomatic with no history of contact with carriers	Find out if the patient has been contaminated before	No indication for testing	-
	Assess the population incidence of virus infection/ immunization	RLT “Rapid Test” (immunochromatography)	-
Asymptomatic after contact with COVID-19 patient	Define quarantine requirement	RT-PCR	Serology after 15-30 days of contact
Patient with early symptoms suggestive of COVID-19 (up to 7 days from symptom onset, ideally between 3-4 days)	Diagnosis of the disease	RT-PCR	Serology (after 15 days of symptom onset)
Patient with symptoms suggestive of COVID-19 with late symptom onset (after day 7 and before 14 days of symptoms)	Diagnosis of the disease	RT-PCR + chest CT	Serology (after 15 days of symptom onset)
Symptomatic or recovered patient, more than 15 days after symptom onset		Serology
The patient recovered from COVID-19, after 7 days	Evaluate return to work of health personnel	RT-PCR	Serology
Patient recovered from COVID-19, more than 14 days after the first symptom onset	Diagnosis (retrospective) of the disease	Serology

Associação Médica Brasileira R. São Carlos do Pinhal, 324, 01333-903 São Paulo SP - Brazil, Tel: +55 11 3178-6800, Fax: +55 11 3178-6816 - São Paulo - SP - Brazil
E-mail: ramb@amb.org.br

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[1] CORRESPONDING AUTHOR: Fernando Antonio Araujo, Faculdade de Medicina da Bahia. Praça XV de novembro, s/n - Largo do Terreiro de Jesus, Salvador, BA, Brasil – 40026-010 Tel: +55 71 3285-5566 E-mail: faraujo.br@hotmail.com