Factors influencing pH1N1 vaccine uptake at the later stage of a pandemic might be more cognitively driven unlike behavioral responses during the early stage of a pandemic which might be more affect driven [52] . Therefore, taking into account prior work on seasonal influenza vaccination uptake [50, 51] , extending the TPB could provide theoretical utility for understanding public decision on taking pH1N1 vaccination. Starting with TPB and existing literature, we therefore built a conceptual model of public decision-making for pH1N1 vaccination ( Figure 3 ). In addition to the original TPB components, seasonal influenza vaccination history, anticipated regret and vaccination planning were included in the model. The model proposed that attitudes towards vaccination (perceived benefits of pH1N1 vaccination and concerns regarding possible adverse effects of pH1N1 vaccination), perceived social pressures from significant others and other people around regarding pH1N1 vaccination (social norms regarding pH1N1 vaccination), perceived self-efficacy in taking vaccination (perceived self-efficacy), anticipated regret for not taking the pH1N1 vaccination (anticipated regret) and seasonal influenza vaccination history would predict vaccination intention, which in turn predicts vaccination planning and future vaccination uptake; anticipated regret and perceived self-efficacy could also predict vaccination status directly; finally, vaccination planning was proposed to bridge the intention-behavior gap and predict vaccination status directly ( Figure 3 ).