1. National Center for Veterinary Diagnostics, Department of Animal Health, Hanoi, Vietnam
2. Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
3. Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA 30333 USA
4. Department of Animal Health, Ministry of Agriculture and Rural Development of Vietnam, Hanoi, Vietnam
5. Food and Agriculture Organization of the United Nations, Hanoi, Vietnam