The researchers believe that most SARS-CoV-2 infections are not permanently asymptomatic, and asymptomatic infections were less infectious than symptomatic. Credit: Monstera, Pexels (CC0, https://creativecommons.org/publicdomain/zero/1.0/)

Based on studies published before July 2021, most SARS-CoV-2 infections were not asymptomatic, and asymptomatic infections were less infectious than symptomatic. These are the findings of an update of a systematic review and meta-analysis published May 26 in an open access journal MEDICINE PLOS Diana Buytraga-Garcia of the University of Bern, Switzerland, and colleagues.

The debate over the level and risks of asymptomatic SARS-CoV-2 infections continues, and numerous studies are ongoing. Studies that evaluate people at only one point in time may overestimate the proportion of true asymptomatic infections because those who later develop symptoms are incorrectly classified as asymptomatic rather than asymptomatic. However, other studies may underestimate asymptomatic infections with study designs that are more likely to involve participants with symptoms.

The new newspaper was a renewal of life (as in, regularly updated) systematic review first published in April 2020, which includes additional, more recent research by July 2021. 130 studies were included with data on 28,426 people with SARS-CoV-2 in 42 countries, including 11,923 people with asymptomatic infection. Due to the extreme variability between the included studies, meta-analysis did not calculate a single estimate of asymptomatic infection, but he estimated the interquartile range in such a way that 14-50% of infections are asymptomatic. In addition, the researchers found that the incidence of secondary attacks – an indicator of the risk of SARS-CoV-2 transmission – was about two-thirds lower in asymptomatic people than in people with symptoms (risk factor 0.32, 95% CI 0.16-0.64).

“If both the incidence and transmission of asymptomatic infection are relatively low, people with asymptomatic SARS-CoV-2 infection should account for a smaller proportion of total transmission than asymptomatic individuals,” the authors say, while emphasizing that “if SARS-CoV -2 in the community is high, it is necessary to observe physical distance and wearing a mask to prevent transmission from close contact with people with asymptomatic and asymptomatic infection ”.

Co-author Nicola Lowe adds, “The true proportion of asymptomatic SARS-CoV-2 infection is still unknown, and it would be a mistake to count on a single figure because the 130 studies we reviewed were very different. People with a truly asymptomatic infection, however, are less infectious than those with a symptomatic one infection».


Most SARS-CoV-2 transmission occurs from asymptomatic individuals


Additional information:
Medicine PLoS (2022). DOI: 10.1371 / journal.pmed.1003987

Citation: asymptomatic SARS-CoV-2 infections, which cause less prevalence of COVID-19 than symptomatic (May 26, 2022), obtained May 26, 2022 from https://medicalxpress.com/news/2022-05-asymptomatic- sars-cov- infections-responsible-covid-.html

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