[1] Soder Hosp, Sachs Childrens Clin, S-11883 Stockholm, Sweden
[2] Vidar Clin, Jarna, Sweden
[3] Karolinska Inst, Ctr Allergy Res, Stockholm, Sweden
[4] Swedish Inst Infect Dis Control, Stockholm, Sweden
[5] Karolinska Inst, Dept Med, Unit Clin Allergy Res, Stockholm, Sweden
[6] Karolinska Hosp, S-10401 Stockholm, Sweden
[7] Karolinska Inst, Microbiol & Tumor Biol Ctr, Stockholm, Sweden
[8] Karolinska Inst, Dept Cell & Mol Biol, Lab Med Microbial Ecol, Stockholm, Sweden
[9] Karolinska Inst, Inst Environm Med, Div Environm Epidemiol, Stockholm, Sweden