Ulrike Protzer, Peter Achenbach, Ezio Bonifacio, Susanne Heck, Merle Boehmer, Franziska Voss, Lisa Holthaus, Anette-Gabriele Ziegler, Martin Heigermoser, Tiziana C. Welzhofer, Joanna Stock, Dominik A. Ewald, F Haupt, Heidi Kapfelsperger, Lorenzo Piemonti, Benjamin A. Marcus, Markus Hippich, Annika Koelln, Jose Zapardiel-Gonzalo, Vito Lampasona, Kathrin de la Rosa, Robin Assfalg, Massimiliano Secchi, Hippich, Marku, Holthaus, Lisa, Assfalg, Robin, Zapardiel Gonzalo, Jose M, Kapfelsperger, Heidi, Heigermoser, Martin, Haupt, Florian, Ewald, Dominik A, Welzhofer, Tiziana C, Marcus, Benjamin A, Heck, Susanne, Koelln, Annika, Stock, Joanna, Voss, Franziska, Secchi, Massimiliano, Piemonti, Lorenzo, Rosa, Kathrin de la, Protzer, Ulrike, Boehmer, Merle, Achenbach, Peter, Lampasona, Vito, Bonifacio, Ezio, and Ziegler, Anette-Gabriele
Background Antibody responses to virus reflect exposure and potential protection. Methods We developed a highly specific and sensitive approach to measuring antibodies against SARS-CoV-2 for population-scale immune surveillance. Antibody positivity was defined as a dual-positive response against both the receptor binding domain and nucleocapsid proteins of SARS-CoV-2. Antibodies were measured by immuno-precipitation assays in capillary blood from 15,771 children aged 1 to 18 years living in Bavaria, Germany, and participating in a public health type 1 diabetes screening program (Clinicaltrials.gov NCT04039945), in 1,916 dried blood spots from neonates in a Bavarian screening study (Clinicaltrials.gov NCT03316261), and in 75 SARS-CoV-2 positive individuals. Virus positive incidence was obtained from Bavarian health authority data. Findings. Dual-antibody positivity was detected in none of 3887 children in 2019 (100% specificity) and 73 of 75 SARS-CoV-2 positive individuals (97.3% sensitivity). Antibody surveillance in children during 2020 resulted in frequencies of 0.08% in January to March, 0.61% in April, 0.74% in May, 1.13% in June and 0.91% in July. Antibody prevalence from April 2020 was six-fold higher than the incidence of authority-reported cases (156 per 100,000 children), showed marked variation between the seven Bavarian regions (P, Graphical Abstract, Highlights • SARS-CoV-2 dual antibody strategy yielded 100% specificity and >95% sensitivity • Childhood surveillance finds 6-fold higher antibody prevalence than reported cases • Half of the antibody positive children were asymptomatic • No association found between SARS-Cov-2 antibodies and type 1 diabetes autoimmunity, Hippich et al developed a highly specific and sensitive dual antibody strategy for public health surveillance of SARS-CoV-2 antibody prevalence. In testing more than 11,000 children in Germany, they report an antibody prevalence that is six-fold higher than the health authority-reported SARS-CoV-2 incidence, including 50% of antibody-positive children without symptoms.