“High SARS-CoV-2 Seroprevalence But No Severe Course of COVID-19 Disease Among People on Opioid Agonist Treatment in Zurich: a Cross-Sectional Study”. Swiss Medical Weekly 152, no. 0102 (January 12, 2022): w30122. Accessed October 30, 2025. https://smw.ch/index.php/smw/article/view/3141.