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.

German and international studies on SARS-CoV-2 seroprevalence.

Since the beginning of the year 2020, the SARS-CoV-2 coronavirus has spread globally at a tremendous pace. Studies on the prevalence of SARS-CoV-2 antibodies in the population help estimate the number of people that have already been infected. They also allow an estimate of the number of undetected infections i.e. infections that do not appear in data on officially reported cases. The interpretation of study results needs to consider bias from selective sampling and the diagnostic test properties. To promote networking and co-operation between scientists, the Robert Koch Institute has compiled an overview of the seroepidemiological studies conducted in Germany on its website, which is regularly updated. The RKI conducts searches, for example of press releases, study registry entries or preprint server publications, and contacts the lead investigators of these studies. Of the 40 studies contacted so far, 24 have already provided information (as of 25.06.2020). We can differentiate between studies of the general population, of selected population groups such as healthcare workers, or of ongoing cohorts. This article provides an overview of such studies from Germany, but also of selected international studies. A special focus is set on studies of children and adolescents, which are now of particular interest due to the planned reopening of childcare facilities and schools.

[Seroprevalence of SARS-CoV-2 among children and adolescents in Germany-an overview]. / SARS-CoV-2-Seroprävalenz bei Kindern und Jugendlichen in Deutschland ­ ein Überblick.

BACKGROUND: SARS-CoV­2 serologic studies complement and expand findings from confirmed COVID-19 cases through identification of undetected cases. OBJECTIVES: This article summarizes previous results on SARS-CoV­2 prevalence from seroepidemiological studies in Germany focusing on children and adolescents and complements the already existing overview on seroprevalence in adults from general population samples and especially blood donors in Germany. METHODS: The results are based on an ongoing systematic search in study registries, in literature databases, of preprint publications, and of media reports of seroepidemiological studies in Germany and their results. RESULTS: As of 17 September 2021, we are aware of 16 German seroepidemiological studies focusing on children and adolescents. Results are available for nine of these studies. For almost all settings studied, SARS-CoV­2 seroprevalence was well below 1% for preschool and elementary school children in the first COVID-19 wave and below 2% for adolescents. As the pandemic progressed, higher seroprevalences of up to 8% were found in elementary school children. DISCUSSION: Results of SARS-CoV­2 antibody studies in children and adolescents in Germany are scarce so far and are based on non-representative samples at local or regional level. In future studies, it is necessary on the one hand to estimate which proportion of children and adolescents has already either had an infection or has been vaccinated. On the other hand, it is important to investigate physical and mental health impairments that occur after an infection.