[1] INST PASTEUR,VIRAL ECOL UNIT,PARIS,FRANCE
[2] DEPT HLTH,LONDON SE1 6TE,ENGLAND
[3] RIVM,DEPT INFECT DIS EPIDEMIOL,BILTHOVEN,NETHERLANDS
[4] CSL LTD,WHO COLLABORATING CTR INFLUENZA,PARKVILLE,VIC,AUSTRALIA
[5] STATE SERUM INST,COPENHAGEN,DENMARK
[6] SBL VACCIN AB,STOCKHOLM,SWEDEN
[7] NATL INST PUBL HLTH,OSLO,NORWAY
[8] NATL INST PUBL HLTH,HELSINKI,FINLAND
[9] DIRECTORATE PUBL HLTH,REYKJAVIK,ICELAND
[10] NATL CTR PHARMACOBIOL,INST HLTH,MADRID,SPAIN
[11] SWISS FED OFF PUBL HLTH,BERN,SWITZERLAND
[12] NATL INST HLTH,NATL INFLUENZA CTR,LISBON,PORTUGAL
[13] INST HYG & EPIDEMIOL,B-1050 BRUSSELS,BELGIUM
[14] UNIV VIENNA,INST SPECIF PROPHYLAXES & TROP MED,VIENNA,AUSTRIA
[15] MINIST HLTH,ROME,ITALY