“Seroprevalence of SARS-CoV-2 Antibodies and Associated Risk Factors in Children Less Than 6 Years of Age in the Canton of Fribourg, Switzerland (COVPED study): A Population-Based Cross-Sectional Study”. Swiss Medical Weekly 152, no. 2122 (May 24, 2022): w30173. Accessed December 3, 2025. https://smw.ch/index.php/smw/article/view/3199.