Nationally representative results on SARS-CoV-2 seroprevalence and testing in Germany at the end of 2020.

Pre-vaccine SARS-CoV-2 seroprevalence data from Germany are scarce outside hotspots, and socioeconomic disparities remained largely unexplored. The nationwide representative RKI-SOEP study (15,122 participants, 18-99 years, 54% women) investigated seroprevalence and testing in a supplementary wave of the Socio-Economic-Panel conducted predominantly in October-November 2020. Self-collected oral-nasal swabs were PCR-positive in 0.4% and Euroimmun anti-SARS-CoV-2-S1-IgG ELISA from dry-capillary-blood antibody-positive in 1.3% (95% CI 0.9-1.7%, population-weighted, corrected for sensitivity = 0.811, specificity = 0.997). Seroprevalence was 1.7% (95% CI 1.2-2.3%) when additionally correcting for antibody decay. Overall infection prevalence including self-reports was 2.1%. We estimate 45% (95% CI 21-60%) undetected cases and lower detection in socioeconomically deprived districts. Prior SARS-CoV-2 testing was reported by 18% from the lower educational group vs. 25% and 26% from the medium and high educational group (p < 0.001, global test over three categories). Symptom-triggered test frequency was similar across educational groups. Routine testing was more common in low-educated adults, whereas travel-related testing and testing after contact with infected persons was more common in highly educated groups. This countrywide very low pre-vaccine seroprevalence in Germany at the end of 2020 can serve to evaluate the containment strategy. Our findings on social disparities indicate improvement potential in pandemic planning for people in socially disadvantaged circumstances.

Corona Monitoring Nationwide (RKI-SOEP-2): Seroepidemiological Study on the Spread of SARS-CoV-2 Across Germany

SARS-CoV-2, the coronavirus, spread across Germany within just a short period of time. Seroepidemiological studies are able to estimate the proportion of the population with antibodies against SARS-CoV-2 infection (seroprevalence) as well as the level of undetected infections, which are not captured in official figures. In the seroepidemiological study Corona Monitoring Nationwide (RKI-SOEP-2), biospecimens and interview data were collected in a nationwide population-based subsample of the Socio-Economic Panel (SOEP). By using laboratory-analyzed blood samples to detect antibodies to the SARS-CoV-2 virus, we were able to identify a history of vaccination or infection in study participants. By combining these results with survey data, we were able to identify groups within the population that are at increased risk of infection. By linking the RKI-SOEP-2 survey data with data from other waves of the SOEP survey, we will be able to examine the medium- to long-term impacts of the COVID-19 pandemic, including effects of long COVID, in diverse areas of life. Furthermore, the data provide insight into the population's willingness to be vaccinated as well as related attitudes and conditions. In sum, the RKI-SOEP-2 survey data offer a better understanding of the scope of the epidemic in Germany and can help in identifying target groups for infection control in the present and future pandemics.