Long-Term Antibody Response to SARS-CoV-2 in Children
Authors: Dunay Gabor A. , Barroso Madalena , Woidy Mathias , Danecka Marta K. , Engels Geraldine , Hermann Katharina , Neumann Friederike S. , Paul Kevin , Beime Jan , Escherich Gabriele , Fehse Kristin , Grinstein Lev , Haniel Franziska , Haupt Luka J. , Hecher Laura , Kehl Torben , Kemen Christoph , Kemper Markus J. , Kobbe Robin , Kohl Aloisa , Klokow Thomas , Nörz Dominik , Olfe Jakob , Schlenker Friderike , Schmiesing Jessica , Schrum Johanna , Sibbertsen Freya , Stock Philippe , Tiede Stephan , Vettorazzi Eik , Zazara Dimitra E. , Zapf Antonia , Lütgehetmann Marc , Oh Jun , Mir Thomas S. , Muntau Ania C. , Gersting Søren W. ,   the C19.CHILD Study Group, Etzold Stefanie , Goebel Ingrid , Günther Armin , Kantor Pia-Sophie , Bandel Lea , Baumanns Markus , Dähler Pia , Dwenger Barbara , Erdmann Annika , Hegselmann Sophia , Hornig Kai , Jipp Johanna , Kirkerup Pia , Krumm Michael , Kurnaz Pelin , Pasterkamp Sabine , Serve Anna , Tegtmeyer Daniel , Terstegen Julia , Wiedling Ceri Theresa , Wingerath Madelaine , Rutkowski Stefan , Winkler Beate , Arndt Florian , Blankenberg Stefan , Diaz Daniel , Hauck Peer , Kozlik-Feldmann Rainer G. , Müller Götz C. , Stark Veronika C. , Wiegand Peter , Aepfelbacher Martin , Cermann Kathrin , Hoffmann Armin , Knobloch Johannes K.-M. , Addo Marylyn M. , Arck Petra , Diemert Anke , Cramer Corinna , Hecher Kurt , Höger Peter , Lordemann Anja Große , Neumann Maria-Dorothee , Hartz Bernd , Kruchen Anne , Müller Ingo , Boettcher Michael , Reinshagen Konrad , Stiel Carolin , Wenke Katharina , Adler Fernandes de Abreu Joana , Bergers Marlies , Blohm Martin , Deindl Philipp , Harbauer Theresa , Rau Cornelius , Singer Dominique , Klokow Marianne , Strauss Julia , Blankenberg Stefan , Schäfer Ines , Vogel Jens , Noelle-Wying Maximilian , Schulze zur Wiesch Julian , Lessel Davor , Schmitt Caroline , Drosten Christian 
Published: September 2022

Almost 2 years into the pandemic and with vaccination of children significantly lagging behind adults, long-term pediatric humoral immune responses to SARS-CoV-2 are understudied. The C19.CHILD Hamburg (COVID-19 Child Health Investigation of Latent Disease) Study is a prospective cohort study designed to identify and follow up children and their household contacts infected in the early 2020 first wave of SARS-CoV-2. We screened 6113 children < 18 years by nasopharyngeal swab-PCR in a low-incidence setting after general lockdown, from May 11 to June 30, 2020. A total of 4657 participants underwent antibody testing. Positive tests were followed up by repeated PCR and serological testing of all household contacts over 6 months. In total, the study identified 67 seropositive children (1.44%); the median time after infection at first presentation was 83 days post-symptom onset (PSO). Follow-up of household contacts showed less than 100% seroprevalence in most families, with higher seroprevalence in families with adult index cases compared to pediatric index cases (OR 1.79, P = 0.047). Most importantly, children showed sustained seroconversion up to 9 months PSO, and serum antibody concentrations persistently surpassed adult levels (ratio serum IgG spike children vs. adults 90 days PSO 1.75, P < 0.001; 180 days 1.38, P = 0.01; 270 days 1.54, P = 0.001). In a low-incidence setting, SARS-CoV-2 infection and humoral immune response present distinct patterns in children including higher antibody levels, and lower seroprevalence in families with pediatric index cases. Children show long-term SARS-CoV-2 antibody responses. These findings are relevant to novel variants with increased disease burden in children, as well as for the planning of age-appropriate vaccination strategies.