An investigation of the impact of universal Hepatitis B Virus (HBV) vaccination among young blood donors in South Africa

Abstract

Background Hepatitis B Virus (HBV) is endemic in South Africa (SA) since more than 70% of the population is exposed, and this poses a significant risk to the South African blood supply. In April 1995, SA introduced universal HBV vaccinations for newborns, who became eligible to donate blood in 2011. The South African National Blood Service (SANBS) reported a 69% decline in the HBV rate in blood donors <20 years of age between 2010 and 2015, while the HBV rate remained relatively unchanged in older donors. The aim of this study was therefore to determine the rate of HBV vaccination in South African blood donors and thereby determine whether the decrease in HBV rates in younger blood donors can be attributed to HBV vaccination. Blood donors are routinely screened for Hepatitis B Virus, Hepatitis C Virus and Human Immunodeficiency Virus using both molecular and serological techniques. In order to determine the HBV vaccination rate, Hepatitis B negative first time blood donors were also tested for antibodies to Hepatitis B surface antigen (Anti-HBs) and antibodies to Hepatitis B core antigen (Anti-HBc). Methods A total of 1072 routine blood donors from SANBS and the Western Cape Blood Service (WCBS) were included in the study. These blood donors were stratified into two groups: the pre-vaccination era donors included 536 donors aged 24-28 years who were born before the introduction of universal HBV vaccination in April 1995, and the post-vaccination era donors included 536 donors aged 18-24 years born after April 1995. The two groups were matched for geographic location, gender and ethnic group. Donors with an Anti-HBs titre greater than 10 IU/L and negative for Anti-HBc were deemed vaccinated. Significance was determined using the Chi square test and multivariable logistic regression. Results Of the 1072 donors included in the study, 275 (25.7%) tested Anti-HBs titre > 10 IU/L and AntiHBc negative and were therefore deemed HBV vaccinated. There were 87/538 (16.2%) in the pre-vaccination era donors and 188/536 (35.1%) in the post-vaccination era donors. In the pre-vaccination era, vaccination rates were highest among White donors (22.5%) and donors from the Free State/Northern Cape (37.1%). In contrast, Asian donors (54.8%) and those from the Northern Zone (41.5%) had the highest vaccination rates in the post-vaccination era. All differences were significant (p<0.0001). Male and female donors had similar vaccination rates in both periods (pre-vaccinationgroup 16.8%, 15.7% (p=0.82), post-vaccinationgroup: 34.8%, 35.4% (p=0.96) respectively. Multivariable analysis, after controlling for geography, gender, and ethnicity showed that donors from the post-vaccination era had a 2.9 times greater odds of being vaccinated than donors born in the pre-vaccination era (OR 2.89, 95%CI, 2.16-3.89). Compared to Coloured donors, White donors had 2.1 times greater odds of being vaccinated (OR 2.1, 95% CI, 1.21-3.65). No statistically significant odds were noted for geography and gender. Summary / Conclusions A quarter of the donors tested showed evidence of being vaccinated for HBV. The HBV vaccination rate increased significantly in younger donors born after the 1995 introduction of universal HBV vaccination in South Africa, indicating programme efficacy. Vaccination rates increased in all population groups in the post-vaccination era, with the greatest increases among Asian and Coloured donors, suggesting better uptake of the programme among these groups. Other than being born in the vaccination era, ethnicity was the only factor independently associated with being vaccinated. As young vaccinated donors make up more and more of the donor panel, it is expected that there will be a significant decrease in HBV rates and a concomitant increase in blood safety. HBV however remains an important public health and blood transfusion issue and continued efforts are required to strengthen the implementation and coverage of HBV vaccination programmes targeting all population groups, including the most vulnerable groups and people living with HIV. In addition, consideration of birth-dose vaccination to prevent new infections and access to affordable treatment options are also key to achieving the goals for HBV elimination in South Africa.