Analysis of a German blood donor cohort reveals a high number of undetected SARS-CoV-2 infections and sex-specific differences in humoral immune response

Abstract

Seroprevalence studies can contribute to a better assessment of the actual incidence of infection. Since long-term data for Germany are lacking, we determined the seroprevalence of immunoglobulin G (IgG) antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in residual plasma samples of 3,759 German regular blood donors between July 2020 and June 2021. Over almost the entire study period, the incidences determined based on our data were higher than those officially reported by the Robert Koch Institute, the public health institute in Germany. Using our serological testing strategy, we retrospectively detected natural infection in 206/3,759 (5.48%; 95% confidence interval (CI): 4.77–6.25) individuals. The IgG seroprevalence ranked from 5.15% (95% CI: 3.73–6.89) in Lower Saxony to 5.62% (95% CI: 4.57–6.84) in North Rhine Westphalia. The analyses of follow-up samples of 88 seropositive blood donors revealed a comparable fast decay of binding and neutralizing anti-SARS-CoV-2 IgG antibodies. The antibody avidity remained at a low level throughout the whole follow-up period of up to 181 days. Interestingly, female donors seem to express a stronger and longer lasting humoral immunity against the new coronavirus when compared to males. Conclusion: Overall, our data emphasizes that seroprevalence measurements can and should be used to understand the true incidence of infection better. Further characterization of follow-up samples from seropositive donors indicated rapid antibody waning with sex-specific differences concerning the strength and persistence of humoral immune response.

Serosurveillance of SARS-CoV-2 in Welsh Blood Donors: Establishment of the surveillance system and results up to November 2022

“…This led to a reduction in testing and, consequentially, case numbers being identified through pre-existing surveillance systems. Donor-based serosurveillance provides continuous information about population immunity regarding SARS-CoV-2 post-pandemic, which has implications for future public health response, adding to the evidence base of how valuable the blood services facilitation of seroprevalence studies is [34,35]. Furthermore, potential for data linkage to public health databases in Wales, as done in Denmark [36], could be valuable for further interpreting the data.…”