Children born to mothers who tested positive for hepatitis B surface antigen were prone to occult HBV infection despite having been immunized shortly after birth in a recent retrospective study.
Researchers evaluated serum samples from 75 HbsAg (HBsAg)-negative children in the Amol region of northern Iran. All patients were born to HBsAg-positive mothers and had been immunized against HBV. The presence of HBV DNA was assessed according to real-time and sensitive standard polymerase chain reaction (PCR) to determine occult HBV infection (OBI).
Of the 75 children, 55 were anti-HBs-positive, nine were anti-HBc- and anti-HBs-positive, and 11 had no serologic HBV markers. OBI was diagnosed in 21 patients, with HBV DNA levels ranging from 77 to 9,240 copies/mL. All 21 patients with OBI were anti-HBs-positive, with five also testing positive for anti-HBC. No participants tested positive for anti-HBc alone. Investigators observed a strong association between HBV levels greater than 1,000 copies/mL and positive standard PCR results (P=.001).
Among the infected patients, 13 had one or more genetic mutations in regions involved with functional and/or immune epitope activity, and 10 had G145R mutations. The G145R mutation was associated with greater HBV DNA levels, with 60% of patients with the mutation indicating viral loads more than 1,900 copies/mL (P=.012).
“Our study is the first report on the prevalence of OBI among a selected high-risk group of children born to HBsAg-positive mothers, particularly from a region with low-to-intermediate prevalence of HBV,” the researchers wrote. “It is suggested that HBsAg negativity is not sufficient to completely exclude HBV DNA carriers. OBI seems to be relatively frequent in immunized children born to HBsAg-positive mothers. Further studies on the clinical significance of OBI, alternative immunization regimens (eg, administration of boosters) or more effective HBV vaccines (a third generation or HBV DNA vaccines) are required.”