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Introduction: The HPV vaccination rate in Japan has been dismally low. Our previous survey work found that mothers in Japan, who have a strong influence over their daughters, often are receptive to the fathers' participation in the family's decision-making process about getting their daughter HPV vaccinated., Methods: We conducted a survey to investigate the nature of the influence of fathers' participation on the mother's decision-making process. From an internet survey panel, we selected a pool of 1,499 eligible mothers who had 12-18 years old daughters. The mothers were randomized into three Groups. To the mothers in Group A, we gave an educational leaflet regarding HPV vaccination and a second leaflet which recommended that they talk with their husbands about the vaccination. To Group B, we gave only the educational leaflet. No leaflets were sent to Group C. A structured survey questionnaire was then distributed through the internet to the mothers., Results: In Groups A, B, and C, their intention to have their daughter receive the HPV vaccine was 21.6%, 20.7% and 8.2%, respectively. The percent of Group A mothers who thought their husband's opinion was important for when they made the decision was significantly higher (70%) than in Group B (56.6%) or Group C (47.1%)., Conclusions: The fathers' participation in the mothers' decision-making does not increase the likelihood of HPV vaccination for their daughters. On the other hand, the educational leaflet proved to be effective for this cause.

In Japan, the trend for cervical cancer at younger ages has been increasing. As a countermeasure, the HPV vaccine was introduced as a routine vaccination in April 2013. However, the Ministry of Health, Labour and Welfare (MHLW) announced a "Suspension of its active inoculation recommendation for HPV vaccine" in June 2013. In 2016, 32 months after that suspension, we conducted survey via Internet and compared the results with our previous ones conducted at 9 and 23 months after suspension (in 2014 and 2015, respectively). We examined the 'time-dependent change' of the 'intention of mothers to inoculate their daughters with the HPV vaccine' in terms of efficacy of external decision-making support. 17.5% of mothers in the first survey replied that they would inoculate their daughters under the current circumstances, 12.1% in the second survey, and 6.7% in the third, showing a consistent decrease in willingness over time (p = 0.03, p < 0.01). If the government recommendation were to be reintroduced, 22.5% of mothers in the first survey replied they would inoculate their daughters, 21.0% in the second survey, which indicated no significant difference (p = 0.65) over the first interval; however, this was significantly decreased to 12.2% in the third survey (p < 0.01). Our study revealed that the intention to inoculate their daughters has been declining among Japanese mothers over time triggered by the suspension.

Objective: In Japan, the possible adverse events upon HPV vaccination was widely reported in the media. MHLW announced the suspension of aggressively encouraging HPV vaccination in 2013, and inoculation rate has sharply declined. The aim of the present study was estimation of future cervical cancer risk., Methods: The latest data on vaccination rate at each age in Sakai City were first investigated. The rate of experiencing sexual intercourse at the age of 12, 13, 14, 15, 16, 17 and throughout lifetime is assumed to be 0%, 1%, 2%, 5%, 15%, 25%, and 85% respectively. The cervical cancer risk was regarded to be proportional to the relative risk of HPV infection over the lifetime. The risk in those born in 1993 whom HPV vaccination was not available yet for was defined to be 1.0000., Results: The cumulative vaccination rates were 65.8% in those born in 1994, 72.7% in 1995, 72.8% in 1996, 75.7% in 1997, 75.0% in 1998, 66.8% in 1999, 4.1% in 2000, 1.5% in 2001, 0.1% in 2002, and 0.1% in 2003. The relative cervical cancer risk in those born in 1994-1999 was reduced to 0.56-0.70, however, the rate in those born in 2000-2003 was 0.98-1.0, almost the same risk as before introduction of the vaccine., Discussion: The cumulative initial vaccination rates were different by the year of birth. It is confirmed that the risk of future cervical cancer differs in accordance with the year of birth. For these females, cervical cancer screening should be recommended more strongly.