Stefano Tancredi, Arnaud Chiolero, Cornelia Wagner, Moa Lina Haller, Patricia Chocano-Bedoya, Natalia Ortega, Nicolas Rodondi, Laurent Kaufmann, Elsa Lorthe, Hélène Baysson, Silvia Stringhini, Gisela Michel, Chantal Lüdi, Erika Harju, Irene Frank, Medea Imboden, Melissa Witzig, Dirk Keidel, Nicole Probst-Hensch, Rebecca Amati, Emiliano Albanese, Laurie Corna, Luca Crivelli, Julia Vincentini, Semira Gonseth Nusslé, Murielle Bochud, Valérie D'Acremont, Philipp Kohler, Christian R Kahlert, Alexia Cusini, Anja Frei, Milo A Puhan, Marco Geigges, Marco Kaufmann, Jan Fehr, Stéphane Cullati
PURPOSE: We aimed to assess the seroprevalence trends of SARS-CoV-2 antibodies in several Swiss cantons between May 2020 and September 2021 and investigate risk factors for seropositivity and their changes over time. METHODS: We conducted repeated population-based serological studies in different Swiss regions using a common methodology. We defined three study periods: May-October 2020 (period 1, prior to vaccination), November 2020-mid-May 2021 (period 2, first months of the vaccination campaign), and mid-May-September 2021 (period 3, a large share of the population vaccinated)...
March 4, 2023: Infection