A national household-based population seroprevalence survey of SARS-CoV-2 antibodies in South Africa in 2020-2021: research report

The World Health Organization (WHO) declared the coronavirus disease (COVID19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a pandemic on 11 March 2020. The first case of SARS-CoV-2 in South Africa was reported on 5 March 2020. By the end of November 2021, South Africa had experienced three waves (periods of increased transmission) of the pandemic (June - August 2020, December 2020 - February 2021 and June - September 2021). During the early stages of the pandemic, surveillance was largely based on the detection of active cases using polymerase chain reaction (PCR) testing. Uncertainty remained about the prevalence of the virus in communities because some individuals were not able to access testing facilities, while others were asymptomatic and therefore remained diagnosed. (Xu et al., 2020, Pollan et al., 2020). Studies that reported on SARS-CoV-2 infections in cloistered or specific settings, showed that many infections were asymptomatic and would remain undetected if testing was prompted by the presence of symptoms alone. These studies used PCR testing and revealed that the proportion of persons who tested positive for COVID-19 whilst asymptomatic ranged between 17.9% and 87.9% (Mizumoto et al., 2020, Sutton et al., 2020, Reuters, 2020, Gudbjartsson et al., 2020). The reverse transcriptase PCR test detects viral particles early on during the active progression of the disease but cannot be used to determine if someone had the infection in the past (Wang et al., 2020).