Nationwide increases in anti-SARS-CoV-2 IgG antibodies between October 2020 and March 2021 in the unvaccinated Czech population

Abstract

Plain Language Summary The nationwide prospective seroconversion (PROSECO) study is monitoring the presence of anti-SARS-CoV-2 IgG antibodies in the Czech population. The presence of these antibodies is indicative of a previous infection with SARS-CoV-2. Here, we report initial results from 30,054 participants in this study that were recruited between October 2020 and March 2021, during the second wave of the COVID pandemic. The data indicates that the percentage of the population infected with SARS-CoV-2 is higher than estimates based on official data on cumulative PCR testing for presence of the virus. At least one third of participants with antibodies did not have symptoms of COVID and 28% had not undergone PCR testing. This study demonstrates the importance of monitoring the presence of anti-SARS-CoV-2 IgG antibodies to accurately assess the proportion of the population that has been infected over time.