[1] VIDRL, WHO Collaborating Ctr Reference & Res Influenza, Melbourne, Vic, Australia
[2] CDC, WHO Collaborating Ctr Surveillance Epidemiol & Co, Atlanta, GA 30333 USA
[3] NIMR, WHO Collaborating Ctr Reference & Res Influenza, London, England
[4] NIID, WHO Collaborating Ctr Reference & Res Influenza, Tokyo, Japan
[5] WHO GIP, Geneva, Switzerland
[6] NIBSC, London, England
[7] CBER, Bethesda, MD USA
[8] TGA, Canberra, ACT, Australia
[9] NIH, Fogarty Int Ctr, Bethesda, MD 20892 USA
[10] Univ Cambridge, Cambridge CB2 1TN, England
[11] St Jude Childrens Res Hosp, WHO Collaborating Ctr Studies Ecol Influenza Anim, Memphis, TN 38105 USA