Effectiveness of prophylactic HPV vaccine for cervical abnormalities and
HPV infection in Japan: the Japanese Human Papillomavirus Disease
Education and Research Survey (J-HERS) 2021
Abstract
Objective: This study investigated the efficacy of the
prophylactic human papillomavirus (HPV) vaccine started at 2009- 2013 in
Japan. Materials and Methods: The study involved 1529 eligible
women aged 16 to 39 years who visited 11 outpatient clinics for various
reasons in Japan. All these patients underwent an examination of HPV
genotype and a Pap test using cervical cell samples. Two hundred
ninty-nine women (19.6%) received the prophylactic HPV vaccine
(bivalent :quadrivalent vaccine ratio = 2:1). Of the 5062 participants
in the Japanese Human Papillomavirus Disease Education and Research
Survey (J-HERS 2011), which was conducted in the pre-vaccination era,
3236 eligible participants were included as controls. Results:
In the present study (J-HERS 2021), highest rate for HPV vaccination
(53%) was observed in 22- to 27-year-old patients. Vaccinated ones
showed 49% protection against low-grade intraepithelial lesions (LSIL)
and atypical squamous cells not excluding high-grade squamous
intraepithelial lesions (ASCH) or worse (LSIL/ASCH+), and 100%
protection against high-grade squamous intraepithelial lesions (HSIL) or
worse (HSIL+). The prevalences of HPV16 and HPV18 infections also
significantly decreased (HPV16; 95% and HPV18; 100%), but there were
no differences in HPV6 and HPV11 infections by the vaccination. The
prevalences of HPV51 and HPV59 increased with vaccination, although
these changes were not confirmed in the comparative study with J-HERS
2011. Comparisons between the pre-vaccination period (J-HERS 2011) and
post-vaccination period (J-HERS 2021) revealed reduction rates of 43%,
51%, 88%, and 62% were observed for HPV16, HPV18, HPV16/18, and
HPV31/58 infections, respectively. Similarly, reduction rates of 62%
and 71% for LSIL/ASCH+ and HSIL+, respectively. The reduction rate for
LSIL/ASCH+ was 88% in 16- to 21-year-old patients, whereas the rate for
HSIL+ was 87% in 28- to 33-year-old patients. C onclusion:
Bivalent or quadrivalent vaccines provided 100% protection against
high-grade squamous cell lesions (suggestive of CIN2 or CIN3) in young
women aged < 39 years at 9 to 12 years after initiation of the
first nationwide HPV vaccination program in Japan. Cross-protection
against HPV31 and HPV58 is likely to occur, although some HPV type
replacements are inconsistent across vaccination regimens. This
demonstrates a high effectiveness of HPV vaccine. In contrast, we worry
about no reduction of cervical cancer in younger generation (born in
1997-2007) who are rarely vaccinated due to long term suspension of this
vaccine recommendation in Japan.