Self administered, anonymous questionnaires were used in both surveys. The questionnaire consisted of five sections with 17 questions: (1) demographics, patient contact, and history of seasonal influenza vaccination in 2008-9; (2) willingness to accept pre-pandemic vaccination with H5N1 vaccine; (3) willingness to accept pandemic vaccination with H1N1 vaccine (the second survey only); (4) perception of risk and seriousness of the pandemic influenza; and (5) suggestions on deployment of duties during pandemic flu, opinion on mandatory vaccination, and the possible ways of disposal for nearly expired vaccines. The participants were requested to send the completed questionnaires via internal mail.