Ulyte, A., T. Radtke, I. A. Abela, S. R. Haile, P. Ammann, C. Berger, A. Trkola, J. Fehr, M. A. Puhan, and S. Kriemler. “Evolution of SARS-CoV-2 Seroprevalence and Clusters in School Children from June 2020 to April 2021: Prospective Cohort Study Ciao Corona”. Swiss Medical Weekly, vol. 151, no. 4546, Nov. 2021, p. w30092, doi:10.4414/SMW.2021.w30092.