[1] Univ Childrens Hosp Zurich, Hosp Epidemiol, Div Infect Dis, Zurich, Switzerland
[2] Univ Hosp Zurich, Hosp Epidemiol, Dept Infect Dis, Zurich, Switzerland
[3] Burgerspital, Frauenklin, Solothurn, Switzerland
[4] Univ Zurich, Inst Med Virol, Zurich, Switzerland
[5] Univ Bern, Bern Univ Hosp, Dept Infect Dis, Bern, Switzerland
[6] Lindenhofspital Bern, Dept Obstet & Gynecol, Bern, Switzerland
[7] Univ Lausanne, Lausanne Univ Hosp, Dept Woman Mother & Child, Unit Pediat Infect Dis & Vaccinol, Lausanne, Switzerland
[8] Univ Bern, Bern Univ Hosp, Dept Pediat, Inselspital, Bern, Switzerland
[9] Univ Geneva, Univ Hosp Geneva, Dept Pediat Gynecol & Obstet, Obstet Div, Geneva, Switzerland
[10] EOC, Inst Pediat Southern Switzerland, Bellinzona, Switzerland
[11] Univ Basel, Univ Hosp Basel, Div Infect Dis & Hosp Epidemiol, Basel, Switzerland
[12] Geneva Univ Hosp, Dept Pediat Gynecol & Obstet, Pediat Infect Dis Unit, Geneva, Switzerland
[13] Univ Hosp Basel, Dept Obstet, Basel, Switzerland
[14] Univ Childrens Hosp Basel, Basel, Switzerland
[15] Cantonal Hosp St Gallen, Dept Infect Dis Infect Prevent & Travel Med, St Gallen, Switzerland
[16] Childrens Hosp Eastern Switzerland, Infect Dis & Hosp Epidemiol, St Gallen, Switzerland