Germany’s Low Sars-Cov-2 Seroprevalence Confirms Effective Containment in 2020: Results of the Nationwide RKI-SOEP Study

Abstract

Pre-vaccine SARS-CoV-2 seroprevalence data from Germany are scarce outside hotspots, andsocioeconomic disparities remained largely unexplored. The nationwide RKI-SOEP study with 15,122adult participants investigated seroprevalence and testing in a supplementary wave of the Socio-Economic-Panel conducted predominantly in October-November 2020. Self-collected oral-nasalswabs were PCR-positive in 0.4% and Euroimmun anti-SARS-CoV-2-S1-IgG ELISA from dry capillaryblood 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 adjusting forantibody decay. Overall infection prevalence including self-reports was 2.1%. We estimate 45% (95%CI 21-60%) undetected cases and analyses suggest lower detection in socioeconomically depriveddistricts. Prior SARS-CoV-2 testing was reported by 18% from the lower educational group comparedto 25% and 26% from the medium and high educational group (p<0.0001). Symptom-triggered testfrequency was similar across educational groups. However, routine testing was more common inlow-educated adults, whereas travel-related testing and testing after contact with an infected personwas more common in highly educated groups. In conclusion, pre-vaccine SARS-CoV-2-seroprevalencein Germany was very low. Notified cases appear to capture more than half of infections but mayunderestimate infections in lower socioeconomic groups. These data confirm the successfulcontainment strategy of Germany until winter 2020.