Conflicts and Changes in Pros and Cons on Twitter in Japan over HPV Vaccine

Abstract

The Japanese government's proactive recommendations for the HPV vaccine, which had been suspended since its introduction in 2013, was announced to resume at the end of 2021, eight years later. This study analyzed how public opinion about the HPV vaccine changed on Twitter, Japan's most popular social media. First, the retweet network analysis confirmed that there was a clear dichotomy between the anti-vaccine group and the pro-vaccine group. It was also shown that the pro-vaccine group, which was initially a minority, became the majority after 2016. Furthermore, we confirmed that there are differences in the external sites that the two groups mainly cite. Based on this, we revealed how public opinion changed over the government's fluctuating policy over vaccines and how the two groups with opposing opinions differed in their behavior.