Neonatal hepatitis B vaccination protects mature adults from occult virus infection

Among elder children/young adults who received hepatitis B virus (HBV) vaccination during infancy, the serological status of HBsAg-negative and anti-HBc-positive [HBsAg(–)/anti-HBc(+)] was frequently reported, indicating potential occult HBV infection (OBI). It is required to define the long-term protection of neonatal vaccination against OBI in their mature adulthood.

Building upon the 1983–1990 established Qidong Hepatitis B Intervention Study, we sampled 10% of the 28–35-year-old participants, who remained in the cohort by 2012. Each participant was tested for serological markers of HBsAg, anti-HBs, HBeAg, anti-HBe and anti-HBc. HBV-DNA and relaxed circular DNA (rcDNA) were determined in some HBsAg(–)/anti-HBc(+) individuals.

Totally, 3615 individuals from the neonatal vaccination group and 3100 individuals from the control group donated blood samples, respectively. In the vaccination group, the prevalence of HBsAg was 1.58% (57/3615), HBsAg(–)/anti-HBc(+) was 4.70% (170/3615), significantly lower than in the control group, which was 7.45% (231/3100) and 19.48% (640/3100) respectively (all p < 0.001). With aging, HBsAg(–)/anti-HBc(+) prevalence increased in the sampled participants from the control group (p_{for trend} < 0.001), but uncertain from the vaccination group. Of HBsAg(–)/anti-HBc(+), HBV-DNA was detected in 13.08% (17/130) from the vaccination group, and in 4.18% (12/287) from the control group. HBV rcDNA was detected in most sera that were tested positive for HBV-DNA.

OBI occurred in some vaccinated adults. However, neonatal HBV vaccination kept the effective protection against OBI in mature adults.