Estimating the extent of asymptomatic COVID-19 and its potential for community transmission : Systematic review and meta-analysis

Copyright © 2020, Association of Medical Microbiology and Infectious Disease Canada (AMMI Canada)..

Background: Knowing the prevalence of true asymptomatic coronavirus disease 2019 (COVID-19) cases is critical for designing mitigation measures against the pandemic. We aimed to synthesize all available research on asymptomatic cases and transmission rates.

Methods: We searched PubMed, Embase, Cochrane COVID-19 trials, and Europe PMC for primary studies on asymptomatic prevalence in which (1) the sample frame includes at-risk populations and (2) follow-up was sufficient to identify pre-symptomatic cases. Meta-analysis used fixed-effects and random-effects models. We assessed risk of bias by combination of questions adapted from risk of bias tools for prevalence and diagnostic accuracy studies.

Results: We screened 2,454 articles and included 13 low risk-of-bias studies from seven countries that tested 21,708 at-risk people, of which 663 were positive and 111 asymptomatic. Diagnosis in all studies was confirmed using a real-time reverse transcriptase-polymerase chain reaction test. The asymptomatic proportion ranged from 4% to 41%. Meta-analysis (fixed effects) found that the proportion of asymptomatic cases was 17% (95% CI 14% to 20%) overall and higher in aged care (20%; 95% CI 14% to 27%) than in non-aged care (16%; 95% CI 13% to 20%). The relative risk (RR) of asymptomatic transmission was 42% lower than that for symptomatic transmission (combined RR 0.58; 95% CI 0.34 to 0.99, p = 0.047).

Conclusions: Our one-in-six estimate of the prevalence of asymptomatic COVID-19 cases and asymptomatic transmission rates is lower than those of many highly publicized studies but still sufficient to warrant policy attention. Further robust epidemiological evidence is urgently needed, including in subpopulations such as children, to better understand how asymptomatic cases contribute to the pandemic.

Medienart:

E-Artikel

Erscheinungsjahr:

2020

Erschienen:

2020

Enthalten in:

Zur Gesamtaufnahme - volume:5

Enthalten in:

Journal of the Association of Medical Microbiology and Infectious Disease Canada = Journal officiel de l'Association pour la microbiologie medicale et l'infectiologie Canada - 5(2020), 4 vom: 15. Dez., Seite 223-234

Sprache:

Englisch

Beteiligte Personen:

Byambasuren, Oyungerel [VerfasserIn]
Cardona, Magnolia [VerfasserIn]
Bell, Katy [VerfasserIn]
Clark, Justin [VerfasserIn]
McLaws, Mary-Louise [VerfasserIn]
Glasziou, Paul [VerfasserIn]

Links:

Volltext

Themen:

Emerging or re-emerging diseases
Epidemiology
Evidence-based medicine
Journal Article
Public health policy
Review

Anmerkungen:

Date Revised 08.11.2022

published: Electronic-eCollection

Citation Status PubMed-not-MEDLINE

doi:

10.3138/jammi-2020-0030

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM348539177