Rigorous hepatitis B surface antigen analyses and identification of hepatitis B chronicity amongst South Africans attending public health facilities over a five-year period: 2015 to 2019

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Abstract Hepatitis B, a potentially life-threatening viral infection of the liver, remains a global public health concern despite the availability of effective vaccines for over three decades. Given that most HBsAg studies targeted distinct cohorts, we aimed to provide HBsAg data nationally in the public health sector of South Africa. We conducted a cross-sectional study on HBsAg tests obtained from the National Health Laboratory Service Central Data Warehouse for tests performed nationally during the period 2015 to 2019. Annual data were cleaned and appended prior to data interrogation to determine and analyse the total number of cases who tested positive for HBsAg and the number of chronic HBV infections. We identified 176,530 cases who tested positive for HBsAg at least once during the 5-year period, with a test positivity rate of 9%. Chronic infections were identified in 6.4% of HBsAg positive cases. Clearance of HBsAg was observed in 5,571 cases, inclusive of clearance in 135 chronic cases. Significantly more males tested positive for HBsAg and were chronically infected (p < 0.0001). Amongst individuals who were vaccine-eligible as infants (0 to 19 years old), 4,980 tested HBsAg positive, of which 22.7% (1,131) were under 5 years old, with a HBsAg population positivity rate of 0.02% and test positivity rate of 4.83%. HBsAg positivity amongst vaccine-eligible individuals is likely due to suboptimal vaccine coverage rates reported for South Africa. Without a birth dose of the HBV vaccine and lack of routine HBsAg screening at antenatal care, it is likely that the majority of HBsAg positive cases under 5 years old were vertically infected. Optimal HBV vaccine coverage, inclusive of a birth dose, is key to eliminating horizontal and vertical transmission of HBV. Early identification of HBV chronicity is fundamental in reducing the risk of liver cirrhosis and hepatocellular carcinoma.

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