Struggles within Japan's national HPV vaccination: A proposal for future strategy.

To the editor,

In Japan, vaccination with public aid against the human papillomavirus (HPV) became available to girls aged 13–16 in 2010. However, early in the spring of 2013, the media began repetitively reporting that adverse patient events might be linked to the vaccine, even though it was not exactly known whether these effects were actually caused by the vaccine. Although, in April of 2013, HPV vaccination was included in the National Immunization Program for girls aged 12–16, the Ministry of Health, Labor and Walfare of Japan suspended its active recommendation for the HPV vaccination in June of 2013. As a result, the HPV vaccination rate in Japan has significantly dropped. A large population of young women unprotected from HPV infection will be genarated due to delays in resuming the national HPV vaccination, because some girls might have sexual intercourse by resuming vaccination encouragement. If the current situation continues in Japan, disparities will occur in the incidence of HPV infections among young women, depending on an unfortunate year of birth. In the future, this cohort gap will result in higher incidences of cervical and other HPV-related diseases.

If, in a few years, Japan resumes its encouragement for some form of HPV vaccination, the vaccination rate will be unlikely to recover immediately. We have studied this issue and found that mothers of vaccine-eligible daughters will tend to delay vaccinating their daughters until after vaccinations have spread safely among their daughters' close friends and acquaintances. Due to this expected lag, simply restarting vaccinations for females aged 12-16 y will be inadequate to reduce the incidence of HPV-related diseases. New national strategies must be developed to address this HPV protection gap. One approach must be focused encouragement for catch-up vaccinations for females in this unprotected cohort. Another would be use of 9-valent HPV vaccines (currently, only bi- and quadrivalent HPV vaccines are licensed in Japan). Lastly, we must begin promoting the HPV vaccines for males, as is done in other countries. Our health agencies should be actively exploring all reasonable actions to reduce the future incidence of HPV-related diseases resulting from our current gap in protecting our youth.