Abstract
Hepatitis B vaccine has contributed to the reduction in hepatitis B virus infections and chronic disease globally. Screening to establish extent of vaccine induced immune response and provision of booster dose are limited in most low-and-middle income countries (LMICs). Our study investigated the extent of protective immune response and breakthrough hepatitis B virus infections among adult vaccinated healthcare workers in selected health facilities in northern Uganda. A cross-sectional study was conducted among 300 randomly selected adult hepatitis B vaccinated healthcare workers in Lira and Gulu regional referral hospitals in northern Uganda. Blood samples were collected and qualitative analysis of Hepatitis B surface antigen (HBsAg), Hepatitis B surface antigen antibody (HBsAb), Hepatitis B envelop antigen (HBeAg), Hepatitis B envelop antibody (HBeAb) and Hepatitis B core antibody (HBcAb) conducted using ELISA method. Quantitative assessment of anti-hepatitis B antibody (anti-HBs) levels was done using COBAS immunoassay analyzer. Multiple logistic regression was done to establish factors associated with protective anti-HBs levels (≥ 10mIU/mL) among adult vaccinate healthcare workers at 95% level of significance. A high proportion, 81.3% (244/300) of the study participants completed all three hepatitis B vaccine dose schedules. Two (0.7%, 2/300) of the study participants had active hepatitis B virus infection. Of the 300 study participants, 2.3% (7/300) had positive HBsAg; 88.7% (266/300) had detectable HBsAb; 2.3% (7/300) had positive HBeAg; 4% (12/300) had positive HBeAb and 17.7% (53/300) had positive HBcAb. Majority, 83% (249/300) had a protective hepatitis B antibody levels (≥10mIU/mL). Hepatitis B vaccine provides protective immunity against hepatitis B virus infection regardless of whether one gets a booster dose or not. Protective immune response persisted for over ten years following hepatitis B vaccination among the healthcare workers.
Highlights
Elimination of hepatitis B virus (HBV) transmission is an achievable public health goal, in the light of proven effectiveness and safety of hepatitis B vaccine [1]
Our study investigated the extent of protective immune response and breakthrough hepatitis B virus infections among adult vaccinated healthcare workers in selected health facilities in northern Uganda
Persistence of hepatitis B antibodies and ability of the immune system to mount a response to exposure of HBV later in life is necessary for long term protection against hepatitis B virus infection [4]
Summary
Elimination of hepatitis B virus (HBV) transmission is an achievable public health goal, in the light of proven effectiveness and safety of hepatitis B vaccine [1]. A substantial decline in HBV-related disease burden and prevalence of chronic HBV infection has been observed among children following introduction of universal infant hepatitis B vaccination [2]. The vaccine may not provide protection from exposure to hepatitis B virus later on in life due to waning of immune memory over time [3]. Persistence of hepatitis B antibodies (anti-HBs) and ability of the immune system to mount a response to exposure of HBV later in life is necessary for long term protection against hepatitis B virus infection [4]. Some studies have confirmed persistence of antibodies and immune memory following hepatitis B vaccination [5] while others confirm waning of antibody concentrations 13–15 years after primary vaccination among those vaccinated at birth [6]. Unless routine post-vaccination serological testing is performed, it remains unclear what proportion of individuals who complete all 3 dose schedules of hepatitis B vaccine get protected, as was found in an earlier study where 22.9% of vaccinated children had undetected antibody levels [7]
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