Immunogenicity and Safety of the 9-valent Human Papillomavirus (HPV) Vaccine Administered as 2-Dose or 3-Dose Regimens in Japanese Boys and Girls Aged 9-15 Years.

Authors

Yuzuru Takeuchi, Motoharu Yonekawa, Shinya Murata, Mariko Nakagomi, Yukako Fukao, Nobuyuki Oshima, Miyuki Sawata

Published in

Japanese journal of infectious diseases. Aug 31, 2026. Epub Aug 31, 2026.

Abstract

A phase III open-label study evaluated the immunogenicity and safety of the 9-valent human papillomavirus (9vHPV) vaccine in Japanese boys and girls. Japanese boys aged 9-15 years (n = 105) received a 3-dose (Day 1, Month 2, and Month 6) regimen; Japanese boys (n = 104) and girls aged 9-14 years (n = 105) received a 2-dose (Day 1 and Month 6) regimen. Antibody responses to HPV6/11/16/18/31/33/45/52/58 were assessed at Month 7, 18, and 30 using a competitive Luminex immunoassay. Injection-site adverse events (AEs; Days 1 to 5 post-dose), systemic AEs (Days 1 to 15 post-dose), and serious AEs (duration of study) were assessed. At Month 7, for HPV types targeted by the 9vHPV vaccine, seroconversion rates were 100% in all three arms, and in cross-study comparisons with efficacy studies, anti-HPV geometric mean titers in boys were noninferior to those in Japanese men aged 16-26 years, and in girls were noninferior to those in Japanese women aged 16-26 years. Most injection-site AEs were mild to moderate in intensity. No deaths or vaccine-related serious AEs were observed. These results support immunobridging of efficacy findings in Japanese men and women to Japanese boys and girls. The 9vHPV vaccine was generally well tolerated.

PMID:
42669546
Bibliographic data and abstract were imported from PubMed on 31 Aug 2026.

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