SARS-CoV-2 infections in 171 countries and over time

Abstract

AbstractUnderstanding the dynamics of the COVID-19 pandemic, evaluating the efficacy of past and current control measures, and estimating vaccination needs, requires knowledge of the number of infections in the population over time. This number, however, generally differs substantially from the number of confirmed cases due to a large fraction of asymptomatic infections as well as geographically and temporally variable testing effort and strategies. Here I use age-stratified death count statistics, age-dependent infection fatality risks and stochastic modeling to estimate the prevalence and growth of SARS-CoV-2 infections among adults (age ≥ 20 years) in 171 countries, from early 2020 until April 9, 2021. The accuracy of the approach is confirmed through comparison to previous nationwide general-population seroprevalence surveys in multiple countries. Estimates of infections over time, compared to reported cases, reveal that the fraction of infections that are detected vary widely over time and between countries, and hence comparisons of confirmed cases alone (between countries or time points) often yield a false picture of the pandemic’s dynamics. As of April 9, 2021, the nationwide cumulative SARS-CoV-2 prevalence (past and current infections relative to the population size) is estimated at 61% (95%-CI 42-78) for Peru, 58% (39–83) for Mexico, 57% (31–75) for Brazil, 55% (34–72) for South Africa, 29% (19-48) for the US, 26% (16–49) for the United Kingdom, 19% (12–34) for France, 19% (11–33) for Sweden, 9.6% (6.5–15) for Canada, 11% (7–19) for Germany and 0.67% (0.47–1.1) for Japan. The presented time-resolved estimates expand the possibilities to study the factors that influenced and still influence the pandemic’s progression in 171 countries. Regular updates are available at: www.loucalab.com/archive/COVID19prevalence