Estimating asymptomatic COVID-19 infections and policy effects

[jim mcnamara]

TL;DR

The estimated asymptomatic population for the full duration of infection is 20%. This has infection control policy implications

If you want to critique this meta-analysis of case studies, please read the article. First. PLOS is open access. Anyone can see it.
Note the ability to see the peer review process, which is interesting.

"Occurrence and transmission potential of asymptomatic and presymptomatic SARS-CoV-2 infections: A living systematic review and meta-analysis"
Diana Buitrago-Garcia, et al.
PLOS MEDICINE Published: September 22, 2020
https://doi.org/10.1371/journal.pmed.1003346

This study implies that we need to consider the continued infection control measures that are in place. This kind of study is not an RCT. It is based on 94 case study papers, sort of a lesser form of scientific rigor. But this is about as good as it gets for this kind of investigation.

Results:

We included a total of 94 studies. The overall estimate of the proportion of people who become infected with SARS-CoV-2 and remain asymptomatic throughout infection was 20% (95% confidence interval [CI] 17–25) with a prediction interval of 3%–67% in 79 studies that addressed this review question. There was some evidence that biases in the selection of participants influence the estimate. In seven studies of defined populations screened for SARS-CoV-2 and then followed, 31% (95% CI 26%–37%, prediction interval 24%–38%) remained asymptomatic. The proportion of people that is presymptomatic could not be summarised, owing to heterogeneity. The secondary attack rate was lower in contacts of people with asymptomatic infection than those with symptomatic infection (relative risk 0.35, 95% CI 0.10–1.27).

Conclusion:

The contribution of presymptomatic and asymptomatic infections to overall SARS-CoV-2 transmission means that combination prevention measures, with enhanced hand hygiene, masks, testing tracing, and isolation strategies and social distancing, will continue to be needed.

 

[waternohitter]

Having a second thought on this!