Open AccessA nationwide birth year‐by‐year analysis of effectiveness of HPV vaccine in Japan
Author(s) -
Yagi Asami,
Ueda Yutaka,
Nakagawa Satoshi,
Masuda Tatsuo,
Miyatake Takashi,
Ikeda Sayaka,
Abe Hazuki,
Hirai Kei,
Sekine Masayuki,
Miyagi Etsuko,
Enomoto Takayuki,
Nakayama Tomio,
Kimura Tadashi
Publication year - 2021
Publication title -
cancer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 1347-9032
DOI - 10.1111/cas.15060
Subject(s) - incidence (geometry) , medicine , vaccination , cervical intraepithelial neoplasia , cervical cancer , demography , hpv infection , pediatrics , obstetrics , cancer , gynecology , immunology , physics , sociology , optics
In Japan, the age‐adjusted incidence of cervical cancer has been increasing constantly and rapidly among younger women. We set out to accurately confirm the effectiveness of the HPV vaccine in Japan. Data were collected for women born in the fiscal year (FY) 1990 to 1997, who became eligible for their 20‐y‐old cervical cancer screening between the FY 2010 to 2017. The adjusted incidence of cervical intraepithelial neoplasia (CIN)1+ in women born in FY 1990 to 1993, that is those who reached the national vaccination target age prior to the introduction of publicly subsidized HPV vaccinations, referred here after as “the pre‐introduction generation”, was 1.42% (242/17 040). The incidence in the “vaccination generation” (women born in FY 1994 to 1997, that is those who were heavily vaccinated as a group when they were of the nationally targeted age of 13‐16) was 1.66% (135/8020). There was no significant difference between these incidence rates. However, our FY birth year‐by‐year analysis revealed that the incidence of CIN1+ was obviously lower than that predicted based on just the trend for CIN1+ seen in the pre‐introduction generation. Our analysis revealed that the incidence of CIN3+ was obviously lower in the vaccination generation than in the pre‐introduction generation ( P = .0008). The incidence of CIN was already tending to increase in both the pre‐introduction and vaccination generations. The changes in CIN incidence by individual birth FY must be examined to accurately determine the actual effects of the HPV vaccine for reducing mild cervical lesions.