The main purpose of this model is to simulate how anti-vaccine opinion leaders in a scale-free network spread their extremism and how it creates anti-vaccine opinion clusters that causes disease outbreaks. The model provides a new way of modeling opinion dynamics and social influence by separating the cyber space and physical space. It identifies that the influence of anti-vaccine opinion leaders is two folded: (1) direct influence: this happens in the cyber space where the large amount of the followers receives information from opinion leaders and get influenced in certain degree; (2) indirect influence: in physical space, those who have been influenced by opinion leaders in cyber space carry such anti-vaccine sentiment and further have an impact in shaping opinions in their local communities. A disease transmission sub-model is applied after these two steps of extremism formation to test the degree of disease outbreaks cause by opinion clustering.