Development of a national agreement on human papillomavirus vaccination in Japan: an infodemiology study.

BACKGROUND: A national agreement on human papillomavirus (HPV) vaccination was achieved relatively quickly in Japan as compared to the United States and India.

OBJECTIVE: The objective was to identify the role of print and online media references, including references to celebrities or other informants, as factors potentially responsible for the relatively rapid national acceptance of HPV vaccination in Japan.

METHODS: A method of text mining was performed to select keywords, representing the context of the target documents, from articles relevant to the promotion of HPV vaccination appearing in major Japanese newspapers and Web pages between January 2009 and July 2010. The selected keywords were classified as positive, negative, or neutral, and the transition of the frequency of their appearance was analyzed.

RESULTS: The number of positive and neutral keywords appearing in newspaper articles increased sharply in early 2010 while the number of negative keywords remained low. The numbers of positive, neutral, and negative keywords appearing in Web pages increased gradually and did not significantly differ by category. Neutral keywords, such as "vaccine" and "prevention," appeared more frequently in newspaper articles, whereas negative keywords, such as "infertility" and "side effect," appeared more frequently in Web pages. The extraction of the positive keyword "signature campaign" suggests that vaccine beneficiaries cooperated with providers in promoting HPV vaccination.

CONCLUSIONS: The rapid development of a national agreement regarding HPV vaccination in Japan may be primarily attributed to the advocacy of vaccine beneficiaries, supported by advocacy by celebrities and positive reporting by print and online media.