Hepatitis B Virus (HBV) prevalence and mother-to-child transmission risk in an HIV early intervention cohort in KwaZulu-Natal, South Africa

Abstract Background HIV and hepatitis B virus (HBV) prevalence are high in KwaZulu-Natal, South Africa. HIV co-infection negatively impacts HBV prognosis, and can increase likelihood of HBV mother-to-child-transmission (MTCT). In an early HIV infant treatment intervention cohort of HIV-transmitting mother-child pairs in KwaZulu-Natal, we characterised maternal HBV prevalence, and screened at-risk infants. Methods Infants were treated for HIV MTCT at birth, and combination regimens incidentally active against HBV were initiated within 21 days. Maternal samples (n = 175) were screened for HBV infection (HBsAg), exposure to HBV (anti-HBc) and vaccination responses (anti-HBs-positive without other HBV markers) at birth. Infants of HBV-positive mothers were screened for HBsAg at 1 and 12 months. Results Evidence of HBV infection was present in 8.6% (15/175) of maternal samples. Biomarkers for HBV exposure were present in 31.4% (55/175). Evidence of HBV vaccination was uncommon in mothers (8.0%; 14/175). Despite prescription of antiretroviral therapy (ART) active against HBV, HBV DNA was detectable in 46.7% (7/15) HBsAg-positive mothers. Three mothers had HBV viral loads >5.3log10 IU/ml, making them high-risk for HBV MTCT. Screening of available infant samples at one month (n = 14) found no cases of HBV MTCT. At 12 months, we identified one HBV infection (1/13) and serological evidence of vaccination was present in 53.8% (7/13) infants. Discussion This vulnerable cohort of HIV-transmitting mothers had a high undiagnosed HBV prevalence. Early infant ART may have reduced risk of MTCT in high-risk cases. Current HBV guidelines recommend ART prophylaxis but these data underline the pressing need to increase availability of birth dose vaccines.