[1] Univ Hosp Geneva, Childrens Hosp Geneva, Dept Paediat, Geneva, Switzerland
[2] Med Fac, Dept Pathol Immunol, Ctr Vaccinol & Neonatal Immunol, Geneva, Switzerland
[3] Univ Hosp Geneva, 1 Rue Michel Servet, CH-1211 Geneva 4, Switzerland
[4] Univ Hosp Geneva, Childrens Hosp Geneva, Dept Neonatol & Paediat Intens Care, Geneva, Switzerland