About HPV vaccine
Cervical cancer generally develops via precancerous lesions (CINs) that are caused by sexually transmitted human papillomavirus (HPV) infections. The HPV vaccine is intended to prevent the development of cervical cancer by preventing its causative HPV infection. In Japan, the vaccines approved so far were bivalent vaccine (Cervarix®) that prevents the infections of two types (HPV types 16 and 18) and quadrivalent vaccine (Gardasil®) that prevents those of four types (HPV types 6, 11, 16, and 18). These vaccines have successfully prevented the infections of HPV types 16 and 18, which account for about 60% of cervical cancers. In May 2020, a nonavalent vaccine (Gardasil 9®) was also approved in Japan. This vaccine successfully prevents the infection of nine types (HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58), which account for about 90% of HPV infections that cause cervical cancer.
Current status of vaccination in Japan
In Japan, public funding for the vaccination for girls aged 13-16 years was started at the end of 2010, resulting in the vaccination rate of as high as about 70%. Routine vaccination for girls aged 12-16 years was started in April 2013. However, "diverse symptoms" after HPV vaccination in girls were repeatedly reported in media, which led to the announcement of withholding its active recommendation in June 2013 by the Ministry of Health, Labor and Welfare. This withholding is still ongoing, with the vaccination rates declining to less than 1%.
The HPV vaccine is extremely effective in preventing the infections of the HPV types mentioned above, with nearly 100% prevention especially when vaccinated before the first sexual intercourse. In countries where HPV vaccine was implemented earlier, preventive effects have been shown for HPV infection, CIN, and HPV-related cancers such as cervical cancer that develops due to HPV infection. Decreases of HPV infection and CIN due to HPV vaccination have already been reported also in Japan. HPV infections have significantly decreased in countries with high vaccination rates, where the herd immunity established has been shown to reduce the chances of HPV infection via sexual intercourse even in unvaccinated people.
The safety of HPV vaccine has been widely recognized overseas. In Japan as well, a national epidemiological survey by Sofue group of the Ministry of Health, Labor and Welfare showed that the "diverse symptoms" were observed even in those who had not received HPV vaccination. A survey in Nagoya reported that there was no significant difference in the incidence of the "diverse symptoms" between vaccinated and -unvaccinated individuals. Based on these results, the causal relationship between HPV vaccination and the "diverse symptoms" is considered negative.
In case of unlikely events of developing the "diverse symptoms" after HPV vaccination, a medical guidance has been published by the Japan Medical Association and the Japanese Association of Medical Sciences. In addition, prefectures have established cooperating medical institutions for providing the vaccination without undue worries.
In Japan, the prevalence of cervical cancer has increased sharply, especially among young women in their 20s-40s, accompanied by the elevation of mortality rate. Early detection/treatment at the CIN stage by cervical cancer screening is important and as such we strongly recommend to receive screening. However, cervical conization (i.e., partial cervical resection) for the treatment of CIN is known to more likely to cause premature birth in subsequent pregnancies. It is important to reduce overall risk of developing CIN and cervical cancer by HPV vaccination.
Elimination of cervical cancer by HPV vaccination and cervical cancer screening is already expected overseas. The World Health Organization (WHO) has criticized Japan by name that the policy decision to withhold the active recommendation of HPV vaccination based on weak evidence will create real damage in the future due to increased cervical cancers that could have been otherwise prevented.
Although the Ministry of Health, Labor and Welfare still maintains the withholding of the active recommendations of HPV vaccination, we would like you to fully understand the actual situation of cervical cancer as well as the efficacy and safety of the HPV vaccine for appropriate preventive actions. Please contact your local gynecological oncologist, if you have any questions.