[1] Inst Hlth Carlos III, Spanish Natl Poliovirus Lab, Natl Ctr Microbiol, Madrid, Spain
[2] Miguel Servet Hosp, Dept Pediat, Zaragoza, Spain
[3] Miguel Servet Hosp, Dept Microbiol, Zaragoza, Spain
[4] Vall dHebron Univ Hosp, Dept Pediat, Barcelona, Spain
[5] Autonoma Univ, Barcelona, Spain
[6] Alvaro Cunqueiro Hosp, Univ Hosp Vigo, Dept Pediat, Vigo, Pontevedra, Spain
[7] Alvaro Cunqueiro Hosp, Univ Hosp Vigo, Dept Prevent Med, Vigo, Pontevedra, Spain
[8] Univ Hosp Germans Trias & Pujol, Sch Med, Barcelona, Spain
[9] Meixoeiro Hosp, Univ Hosp Vigo, Dept Microbiol, Vigo, Spain
[10] Vall dHebron Univ Hosp, Vall dHebron Res Inst, Dept Microbiol, Barcelona, Spain
[11] Santa Creu & St Pau Hosp, Dept Microbiol, Barcelona, Spain
[12] Inst Hlth Carlos III, Natl Ctr Epidemiol, Madrid, Spain
[13] CIBERESP, Madrid, Spain