Univ Lund, Dept Infect Dis & Med Microbiol, Div Infect Dis, SE-22185 Lund, Sweden Dept Microbiol, Linkoping, Sweden Med Prod Agcy, Uppsala, Sweden Karolinska Inst, Dept Clin Virol, Huddinge, Sweden Karolinska Inst, Dept Clin Pharmacol, Huddinge, Sweden Dept Paediat, Boras, Sweden Karolinska Inst, Dept Clin Microbiol, Stockholm, Sweden Staten Legmiddelskontroll, Oslo, Norway Univ Uppsala Hosp, Dept Infect Dis, S-75185 Uppsala, Sweden Univ Lund, Dept Infect Dis, Lund, Sweden Karolinska Inst, Dept Paediat, Huddinge, Sweden Karolinska Inst, Dept Haematol, Huddinge, Sweden Dept Paediat, Lund, Sweden Swedish Inst Infect Dis Control, Solna, Sweden Gothenburg Univ, Dept Paediat, Gothenburg, Sweden Univ Uppsala Hosp, Dept Paediat, S-75185 Uppsala, Sweden Med Prod Agcy, Uppsala, Sweden Karolinska Inst, Dept Paediat, Stockholm, Sweden Karolinska Inst, Dept Infect Dis, Huddinge, Sweden.