*First survey conducted April 10–13 and 25–27, 2013; second survey conducted December 4–8, 2013. p values were estimated by comparing anxiety and risk perception between the 2 surveys after adjustment for demographics including age, sex, education, place of birth, marital status, and household income. SARS, severe acute respiratory syndrome.
†Measured by 4-point State Trait Anxiety Inventory (5; 1 indicates least anxiety, 4 most anxiety).
‡Absolute susceptibility was examined by asking how likely the survey participant thought it was that he or she would contract influenza A(H7N9) during the next month; relative susceptibility was examined by asking how likely the survey participant thought it was that he or she would contract influenza A(H7N9) during the next month compared with persons outside his or her family with similar age. Answers were given on a 7-point scale and measured as proportion of respondents whose answer was likely, very likely, or certain.
§Perceived severity was examined by asking respondents how the severity of influenza A(H7N9) compared with that of seasonal influenza, SARS, and influenza A(H5N1). Answers were given on a 5-point scale and measured as proportion of respondents whose answer was either a bit higher or much higher.
¶Perceived anxiety level if respondent were to experience onset of influenza-like symptoms in the next day. Answers were given a 7-point scale and measured as proportion of respondents whose answer was worried more than normal, worried much more than normal, or extremely worried.