Hepatitis B Virus Infection Status in Japanese Children Prior to Universal Vaccination: Sustained Effectiveness of Mother‐to‐Child Transmission Prevention and Residual Infection Burden
Aiko Sakai, Yasuhito Tanaka, Hiroshi Yotsuyanagi, Masaya Sugiyama, Ichiro Morioka, Kiyotaka Kosugiyama, Kimiaki Uetake, Tomohiro Katsuta, Atsushi Imamura, Tomoko Takano, Hitoshi Tajiri, Akihito Ishida, Kosuke Ushijima, Yumiko Nakashima, Hiroyuki Moriuchi, Shinji Iwane, Kota Sawada, Yosuke Shimizu, Yukari Uemura, Manabu Tagawa, Masashi Mizokami, Ryo SumazakiABSTRACT
Aim
To evaluate the effectiveness of prevention of mother‐to‐child transmission (PMTCT) over 25 years, we conducted a nationwide epidemiological survey through a comprehensive assessment of hepatitis B virus (HBV) markers.
Methods
Two cohorts were recruited before universal vaccination: children aged 9–10 years undergoing school health checkups (Group 1) and hospital patients 0–15 years of age from 11 hospitals across Japan to assess age and regional differences (Group 2). Hepatitis B surface antigen (HBsAg) and core antibody (anti‐HBc) were measured in both cohorts. HBV‐DNA was tested to evaluate occult HBV infection and viral genotypes in Group 2. Anti‐HBs antibody was measured to estimate HBV vaccine coverage.
Results
In Group 1 and Group 2, 8125 and 8453 samples were collected, respectively. HBsAg prevalence was 0% in Group 1 and 0.047% in Group 2 using a conventional assay (Lumipulse II HBsAg). Most HBsAg‐positive samples were from children < 4 years. HBsAg‐negative and anti‐HBc‐positive samples were detected in 0.42% of Group 1 and 0.95% of Group 2. Among these samples in Group 2, 10.3% were HBV‐DNA‐positive, indicating occult HBV infection. Genotype C predominated; however, four genotype D cases were identified in Hokkaido. Anti‐HBs positivity among HBV‐uninfected samples at ages 1, 2, 5, 10, and 15 years was 53.4%, 27.5%, 7.5%, 5.6%, and 1.9%, respectively.
Conclusions
Following the implementation of PMTCT measures in Japan, the prevalence of HBsAg‐positive children was extremely low. However, the prevalence of occult infection and anti‐HBc positivity indicated that some children remained exposed to HBV. To further eradicate HBV infection, universal vaccination was introduced nationwide in 2016.