[1] Univ Zurich Hosp, Div Infect Dis, Zurich, Switzerland
[2] Univ Zurich Hosp, Hosp Epidemiol, Zurich, Switzerland
[3] Univ Lausanne Hosp, Infect Dis Serv, Lausanne, Switzerland
[4] Univ Lausanne, Lausanne, Switzerland
[5] Univ Geneva, Transplantat Serv, Dept Surg, Univ Hosp Geneva, CH-1211 Geneva 4, Switzerland
[6] Univ Basel Hosp, Div Infect Dis, Basel, Switzerland
[7] Univ Basel Hosp, Hosp Epidemiol, Basel, Switzerland
[8] Univ Basel, Transplantat & Clin Virol Div, Dept Biomed, Inst Med Microbiol, CH-4003 Basel, Switzerland
[9] Univ Hosp Bern, Univ Clin Infect Dis, Bern, Switzerland
[10] Cantonal Hosp St Gallen, Div Infect Dis, St Gallen, Switzerland
[11] Cantonal Hosp St Gallen, Hosp Epidemiol, St Gallen, Switzerland
[12] Univ Zurich Hosp, Inst Clin Chem, Zurich, Switzerland
[13] Cantonal Hosp Graubunden, Internal Med, St Gallen, Switzerland
[14] Univ Zurich Hosp, Dept Geriatr, Zurich, Switzerland
[15] Swiss Transplant Cohort Study, Zurich, Switzerland