Questionnaire

The study tool used in this study was a questionnaire adopted and modified from the US CDC cross-sectional survey (http://www.cdc.gov/flu/fluvaxview/national-flu-survey.htm).

The investigation was conducted via face to face interviews. The questionnaire included questions on socio-demographic variables, the health status, the influenza vaccination status during the latest influenza season, and the reason(s) for being or not being vaccinated. For those participants who had received the influenza vaccine, the list of reasons in our questionnaire was read by the investigator and the respondent were asked to select the important reason(s) that influenced their decision. For those who had not received the influenza vaccine, they would first be asked if they had heard about the influenza vaccine. If the answer was “no”, other reasons for not receiving the influenza vaccination were not be proposed. Otherwise, they could provide multiple reasons for not being vaccinated. For those whose vaccination status had been classified as ‘unknown’, the rest of the questionnaire would not be administered.

The questionnaire was validated in a pilot survey conducted in two communities for two months prior to the formal survey.