Rouge Elton, Paola A., Patrick A. Schmitt, Mohamed Faouzi, Petra Zimmermann, and Céline Ritter Schenk. “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 April 20, 2024. https://smw.ch/index.php/smw/article/view/3199.