Resumption of active recommendation of the human papillomavirus vaccine in Japan and future challenges for the National Immunization Program

Japan’s immunization program resumed proactively recommending the use of the human papillomavirus (HPV) vaccine nationwide in April 2022, after suspending this recommendation in June 2013. The promotion of catch-up vaccinations is an urgent issue to reduce the increase in cervical cancer and other cancers caused by low vaccination rates. In addition, the National Immunization Program still has issues to be considered, such as the adoption of the 9-valent vaccine, establishment of an appropriate number of vaccinations according to age, and routine immunization of males. There is a history of eliminating the use of the measles, mumps, and rubella vaccine and the mouse brain-derived, purified inactivated Japanese encephalitis vaccine, as well as suspending the HPV vaccine recommendation in Japan. These decisions have led to the current preventable infectious disease burden. In order to make the right policy decisions based on science-based assessments, it is necessary to establish a safety assessment platform to evaluate the causal relationship between vaccines and adverse events following immunization. Information technology, which has been promoted with the coronavirus disease 2019 vaccine in the current pandemic, may assist in providing more detailed vaccine safety evaluations for other vaccines

Effect of temperature on the infectivity of COVID-19

OBJECTIVES To evaluate the influence of temperature on the infectivity of COVID-19 in Japan. METHODS We evaluated the relationship between the accumulated number of patients per 1,000,000 population and the average temperature in February 2020 in each prefecture by Poisson regression analysis. We introduced the monthly number of inbound visitors from China in January 2020 in each prefecture and old-age dependency ratio as additional explanatory variables in the model. RESULTS Monthly inbound visitors from China in January 2020, old-age dependency ratio, and mean temperature in February 2020 are associated with the cumulative number of COVID-19 case on March 16, 2020. CONCLUSIONS Our analysis showed a possible association between low temperature and increased risk of COVID-19 infection. Further evaluation would be desirable at a global level

Changing trends in HPV vaccination in Japan

After the Japanese Ministry of Health, Labor and Welfare (MHLW) suspended its recommendation for the human papillomavirus (HPV) vaccine in June 2013, the rate of members of the new target population receiving of at least one of three doses of HPV vaccine declined, reaching 0.3% in 2016. Recently, however, the monthly number of vaccines delivered to healthcare facilities has significantly increased, from 878 doses over December 2016–April 2017 to 35,396 doses over January–March 2021. This may be due to governmental efforts to convey information about the HPV vaccination to the eligible population and their caregivers, as well as local educational programs, despite ongoing suspension of the recommendation. The incidence of reported adverse events per vaccine dose has not increased since 2016. While governmental recommendation of the HPV vaccination remains essential for optimal vaccine coverage, the recent increase in the number of doses delivered to healthcare facilities is promising

An open-label, non-randomized study investigating the safety and efficacy of smallpox vaccine, LC16, as post-exposure prophylaxis for mpox

Mpox is an acute exanthematous disease caused by the monkeypox virus. Since May 2022, it has spread as a community-acquired infection, mainly in Europe and the United States, and urgent measures to prevent this infection were also required in Japan. In this study, we investigated the post-exposure prophylaxis of mpox and safety after inoculating the smallpox vaccine. Participants in close contact with patients with mpox were inoculated with “Freeze-dried cell culture Smallpox Vaccine LC16,” within 14 days after close contact. Six cases were registered, and all the participants were inoculated. No mpox symptoms or related complications were observed in the participants for 21 days after the close contact. Adverse events due to inoculation, such as rash, fever, lymphadenopathy, and local reaction at the inoculation site (comprising erythema, swelling, induration, and pain) were observed in the participants; however, all inoculation-related events were non-severe and non-serious, and the participants recovered during the 28-day observation period. The findings of this study suggest that inoculation with LC16 is an effective post-exposure prophylaxis in individuals who had close contact with patients with mpox. Further large-scale studies are warranted to validate these findings