Perinatal HBV infection ‘nearly eliminated’ with Japan’s selective vaccination program
medwireNews: The Japanese nationwide selective vaccination strategy has led to a substantial reduction in perinatal hepatitis B virus (HBV) transmission, say researchers who evaluated the prevalence of hepatitis B surface antigen (HBsAg) among pregnant women born before and after its implementation.
The vaccination program was initiated in 1986 and involves the inoculation of babies born to mothers positive for HBsAg with anti-HBsAg human immunoglobulin and HBV vaccines, they explain.
The study included data on 15,233 pregnant women aged 13–48 years who underwent HBsAg testing at one of 41 obstetric and gynecologic hospitals or clinics in Hiroshima prefecture. Of these, 78 tested positive for the antigen, giving an overall prevalence of 0.51%.
However, when participants were stratified by age, the HBsAg prevalence was “extremely low” among those born after 1986, at rates of 0.12% and 0% for women born between 1986 and 1990 and after 1991, respectively, report Junko Tanaka, from Hiroshima University, and team.
This compared with rates of 0.34%, 0.52%, 0.82%, and 1.84% for women categorized in the 1981–1985, 1976–1980, 1971–1975, and 1970–1975 birth cohorts, respectively.
Highlighting that only two women born after 1986 were HBsAg-positive, the study authors comment that “[t]his finding suggests that the selective vaccination program implemented in 1986 has nearly eliminated the incidence of perinatal HBV infection.”
They believe that the program has been effective “because of the established medical environment, supportive economic conditions, and efforts of medical workers, all of which have led to the near abrogation of vertical HBV transmission.”
However, horizontal transmission to infants has not been eradicated completely and new cases of genotype A infections have been reported among adults, especially those living in urban areas, since 2000, note Tanaka et al.
In order to tackle these issues, “a universal vaccination program of all newborns was implemented in Japan on 1 October 2016,” they write in Hepatology Research.
The team continues: “Because hepatitis B can be prevented with vaccination, these political measures are expected to have successful outcomes in the future.”
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