Hepatitis B Virus (HBV) prevalence and characteristics in HIV-transmitting mothers and their infants in KwaZulu-Natal, South Africa

Background HIV and hepatitis B virus (HBV) prevalence are high in KwaZulu-Natal (KZN), South Africa. HIV co-infection negatively impacts HBV prognosis, and can increase likelihood of HBV mother-to-child-transmission (MTCT). In an established early treatment intervention cohort of HIV-transmitting mother-child pairs in KZN, we characterised HBV serological makers in mothers, and screened at-risk infants for HBV. Methods 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). Infants of HBV-positive mothers were screened for HBsAg at 1 and 12 months. Results HBV infection was present in 8.6% (15/175) of mothers. Biomarkers for HBV exposure were present in 31.4% (55/175), but absent in 53.3% (8/15) maternal HBV-positive cases. Maternal HBV vaccination appeared rare (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, with (5/7) also viraemic for HIV. Three mothers had HBV viral loads >5.3log 10 IU/ml, making them high-risk for HBV MTCT. Screening of available infant samples at one month of age (n=14) found no cases of HBV MTCT, and at 12 months (n=13) identified one HBV infection. Serological vaccination evidence was present in 53.8% (7/13) infants tested. 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 antenatal antiviral prophylaxis but these data underline a potential role for infant post-exposure prophylaxis in high-risk MTCT pairs, warranting further investigation.