Impacts of influenza vaccination policy for the elderly and the SARS epidemic on influenza-like illness in Taiwan

Abstract The effectiveness of influenza vaccination on influenza-like illness (ILI) incidences has been controversial, and requires further studies. In Taiwan, a severe infectious disease epidemic, for example, the severe acute respiratory syndrome (SARS) has been speculated to have impacts on ILI incidences, which has not yet been systematically assessed. This study evaluates the impacts of influenza vaccination policy for the elderly (age ≥ 165 yrs) and the SARS epidemic on ILI in Taiwan by using the weekly ILI surveillance data reported by sentinel physicians in Taiwan. The data were reported by sentinel physicians across all cities and counties in Taiwan. An autoregressive-integrated moving average (ARIMA) model with intervention analysis, which is also referred to impact analysis, was employed to evaluate the impacts of these events. The impact estimates were jointly estimated with outlier effects and other model parameters. The estimates of the two event impacts are statistically significant (p-valu...