Lower Incidence of Cervical Intraepithelial Neoplasia among Young Women with Human Papillomavirus Vaccination in Miyagi, Japan

Abstract

The Japanese national immunization programme for Human Papillomavirus (HPV) started in 2010. Vaccination rates increased up to 70% in women in the 1996-1999 birth. However, the proactive recommendation for HPV vaccine was suspended in 2013, following repeated media reports of adverse events. Vaccination rates plumped to less than 1% in women born since 2002. In this study, incidence of abnormal cytology and histology was examined in terms of HPV vaccination among 5,924 women aged 20 to 24 years in the fiscal year (FY) 2014 and 2015. The total rate of vaccination was 16.9% (1,002/5,924). In case of FY 2015, the rates of vaccination were 59.26%, 49.68%, 11.97%, 9.08%, and 4.58% in those aged 20, 21, 22, 23, and 24 years old, respectively. The rates of high-grade squamous intraepithelial lesion (HSIL) or worse were 0.20% (2/1,002) in women with HPV vaccination and 1.14% (56/4,922) in those without HPV vaccination, indicating a significant reduction of 82.46% with vaccination (P < 0.0001). The rates of cervical intraepithelial neoplasia (CIN) 1+ were 0.80% (8/1,002) in women with vaccination and 2.28% (112/4,922) in those without vaccination. The reduction rate of CIN1+ was 64.91% (P = 0.0025). The rates of CIN2+ were 0.10% (1/1,002) with vaccination and 0.69% (34/4,922) without vaccination. The reduction rate of CIN2+ was 85.51% (P = 0.0261). Our data are the first to demonstrate a significant reduction of CIN2+ cases in an Asian population. Scientific discussion is needed to restart the proactive recommendation for HPV vaccine in Japan.

Effectiveness of catch-up human papillomavirus vaccination on incident cervical neoplasia in a US health-care setting: a population-based case-control study

“…Few epidemiologic studies have evaluated the population effectiveness of HPV vaccination for CIN2+. 21–24,28 A large study in Scotland 22 evaluated the effectiveness of the bivalent HPV vaccine and noted a 50% reduction in CIN2 and 55% reduction in CIN3 for girls ages 13–17 years vaccinated with 3 doses compared with no vaccination; these effects attenuated with increasing age. An Australian study evaluated vaccine effectiveness in girls ages 12–17 (mean age 16 years) and noted a statistically significant 28% reduction in CIN2+ for ≥1 vaccine doses, similar in magnitude to our results, with reduced protection for girls vaccinated at older ages.…”

Human Papilloma Virus, its Vaccine Significance, Side Effects, and Complications

“…Regarding the efficacy of the vaccine, Ozawa et al has stated that HPV vaccines cause a significant decrease in the incidence of abnormal cytological findings of the cervix compared to females who weren't vaccinated. More significantly, a significant reduction has also been observed within the diagnosis of cervical intraepithelial neoplasia-2 or worse, histologically [10].…”

“…Moreover, the search was limited to recent studies from 2016 to 2021 on the topic. The relevant articles have been included in this review as per the following: HPV-related diseases and cancers (2 articles [7,8]), viral cytology (2 articles [9,10], current vaccines and their development (3 articles [4, 11, 12]), and vaccine safety concerns and potential side effects (7 articles [13][14][15][16][17][18][19]). (See References).…”

HPV vaccination in Japan: what is happening in Japan?

“…In regard to the vaccine's efficacy, it has been demonstrated that HPV vaccination leads to a significant reduction in the incidence of abnormal cervical cytological findings, compared to those who were unvaccinated. And more importantly, a significant reduction has been seen in the histological diagnosis of CIN2 or worse [17,18]. A dynamic decrease has been demonstrated in the year-over-year rate of abnormal screening results in association with the introduction of the HPV vaccine, i.e., for the birth-year-dependent change in cervical cancer risk 19 .…”