Hepatitis B virus infection and vaccine coverage among children living with HIV, HIV-exposed uninfected, and HIV-unexposed uninfected children in the Western Cape, South Africa

Background: Limited evidence on the burden of hepatitis B virus (HBV) infection among children living with HIV (CLWH), HIV-exposed uninfected (HEU) and HIV-unexposed uninfected (HUU) children hinders progress towards eliminating hepatitis B. Methods: This study used secondary data and archival sera (N = 671) from children <13 years old attending health facilities in the Western Cape, South Africa. Hepatitis B vaccine coverage was assessed using vaccination records for doses 1 to 3 by 12 months of age. Timely uptake was defined as receipt of a dose from 4 days before to 28 days after the recommended age. Serological markers of infection and immunity were measured using Elecsys® test kits (Roche Diagnostics, Germany). Logistic regression was performed to assess factors associated with incomplete and delayed vaccination. Results: Coverage with all three doses by 12 months was 86.7 % (13/15), 80.9 % (263/325), and 77.0 % (57/74) for CLWH, HUU, and HEU, respectively. Hepatitis B vaccine coverage decreased across all subgroups as the schedule progressed. The highest proportion of delayed uptake for the third dose was noted among CLWH at 23.1 % (3/13), followed by 21.6 % (58/269) among HUU and 15.3 % (9/59) among HEU children (p = 0.540). Median delay for dose 3 was longest among CLWH (11.3 weeks) compared to HUU (6.7 weeks) (p = 0.368). HBV infection was detected in 1.4 % (1/74) of HEU and 0.3 % (1/328) of HUU children, with no cases among CLWH. Factors associated with completing the third dose included crèche attendance, lower-middle socio-economic status (SES), timely uptake of dose 1, participant's age, and HIV exposure status. Crèche attendance was associated with a lower likelihood of delayed uptake, while increasing age was associated with a higher likelihood of delay. Conclusion: Our findings highlight disparities in timely hepatitis B vaccine uptake and coverage, emphasizing the need for targeted interventions ensuring timely vaccine uptake among HIV-exposed children.