Hepatitis B immunity and response to booster vaccination in South African students following childhood immunisation

Abstract

Background: Despite the introduction of hepatitis B virus (HBV) vaccination into the South African Expanded Programme on Immunization in 1995, HBV remains an important occupational risk to healthcare workers and students. Data regarding the duration and level of HBV immunity following childhood vaccination and response to booster vaccination are required to guide vaccination policies. Objectives: The study aimed to investigate pre- and post-vaccination immunity to hepatitis B in healthcare students born after implementation of infant immunisation. Method: Healthcare students were recruited from the Central University of Technology and the University of the Free State in Bloemfontein, South Africa. Hepatitis B surface antibody (HBsAb) levels were determined at baseline, month one and month seven, while booster vaccines were administered at 0 month, 1 month and 6 months. Hepatitis B total core antibody (HBcAb) was also tested at baseline. A total of 122 students were enrolled into the study from approximately 320 eligible students. Two participants did not return following the baseline visit, and one additional participant did not return for the final sampling visit. Results: At baseline, only 43% (n = 52/122) of participants had HBsAb levels which are considered to provide adequate protective immunity. Following a single booster, 92% (n = 111/120) of healthcare students had protective HBsAb levels, which increased to 100% (n = 119/119) following three vaccine doses. No significant differences were observed when HBsAb results were grouped by race or sex. Only one case of previously resolved HBV was identified. Conclusion: The study confirmed persistence of immunological memory in most healthcare students following childhood vaccination, as evidenced by anamnestic responses to a single dose of HBV vaccine. Contribution: Laboratory confirmation of adequate responses is essential to identify those requiring further vaccination and ensure protection in the event of HBV exposure.