[1] ERASMUS UNIV ROTTERDAM, NATL INFLUENZA CTR, 3000 DR ROTTERDAM, NETHERLANDS
[2] NATL INST PUBL HLTH & ENVIRONM PROTECT, VIROL LAB, 3720 BA BILTHOVEN, NETHERLANDS
[3] NATL INFLUENZA CTR, BILTHOVEN, NETHERLANDS
[4] NETHERLANDS INST PRIMARY HLTH CARE, 3500 BN UTRECHT, NETHERLANDS
[5] UNIV ROTTERDAM HOSP, DEPT VIROL, ROTTERDAM, NETHERLANDS
[6] SOPHIA CHILDRENS UNIV HOSP, DEPT PAEDIAT, ROTTERDAM, NETHERLANDS