The World Health Organization recommended a stepwise use of pH1N1 vaccines for protecting people against the pH1N1 influenza pandemic in July 2009 [63] . However, a vaccination program's efficacy largely depends on the public's compliance. Our study found that only 5% of 1,511 subjects reported having received pH1N1vaccination and of 1,433 subjects remaining unvaccinated, only 8% reported intending (being likely/very likely/certain) to take the pH1N1 vaccine. Two months later in the follow-up survey, an even smaller proportion, 0.8% of the respondents who completed both the baseline and follow-up survey reported having been vaccinated against pH1N1. Perceived low risk of pH1N1 and concerns regarding vaccine-related adverse effects were the two most frequently cited reasons for refusing the vaccination. The extended TPB model suggests that both the original TPB components and the additional components contribute to people's decisions on vaccination uptake but that social norms and anticipated regret for not taking vaccination were the strongest determinants of vaccination intention and vaccination planning. Finally vaccination planning partially-mediated the relation between intention and reported vaccination uptake.