Application of the Euroimmun anti-SARS-CoV-2-S1-IgG ELISA antibody test to dried blood spots

The qualitative Euroimmun anti-SARS-CoV-2-S1-IgG ELISA antibody test has been most commonly used in the analysis of serum samples since early 2020. In the population-based seroepidemiological study 'CORONA-MONITORING bundesweit' (RKI-SOEP study) [1], however, it is used to analyse dried blood spots (DBS). A method study was therefore conducted comparing serum with dried blood, embedded in the 'CORONA-MONITORING lokal' study [2]. This method study comprised 276 individuals who had participated both in the baseline survey in May/June 2020 and in the follow-up survey of the study 'CORONA-MONITORING lokal' in October 2020. The sample was made up of individuals who either had a positive or indeterminate IgG test result in serum measurements at the time of the baseline survey (n = 265) or had a negative test result but reported a positive PCR test before the baseline survey in the questionnaire (n = 11)