Prevalence of protective levels of anti-HBs antibodies among 15-17 year old adolescents at kawempe division,Kampala,Uganda

Abstract

BACKGROUND: Viral hepatitis is a global pandemic and HBV is one of the leading causes of liver-related cancer and cirrhosis. The inclusion of the HBV vaccine in National Immunization programs has contributed to the reduction of HBV infection worldwide. However, HBV-endemic countries such as Uganda still have to curb precurring infections especially adolescents who are prone to indulgence in predisposing socio-behavioural activities. In most World Health Organization (WHO) low- and middle-income countries, the rate of deterioration of anti-Hepatitis B surface (HBs) antibodies from childhood vaccination till adolescence is unequivocally known, Hence the proportion of HBV susceptible adolescents is also not known, A matter of public health concern. We intend to investigate and generate data on prevalence of protective levels of anti-HBs antibody titers among the adolescent population in Kawempe division, Kampala, Uganda.OBJECTIVES: This study sought to determine the prevalence of breakthrough HBV infections (Exposure, Acute and chronic) amongst vaccinated 15–17-year-old adolescents in Kawempe division, Kampala, Uganda and also determined the prevalence of protective levels of vaccine specific anti-HBs antibody titers amongst 15–17-year-old adolescents in Kawempe division, Kampala, Uganda.METHODS: A cross sectional study that was nested in a parent study titled “Childhood responses to Hepatitis B vaccine in Uganda; The role of Human Leukocyte Antigen (HLA) and T-Cell Receptor (TCR) diversity”, coded as HBV-HLA/TCR study. The HBV-Combo test was carried out in the Immunology and Molecular Biology Laboratories of the College of Health Sciences; Makerere University sequentially to answer objective 1, The Chemiluminescence Immuno Assay (CLIA) Cobas E411 was used to answer objective two. According to Kish and Leslie's formula, This study vitalized a sample size of 288 participants. RESULTS: We processed 288 serum samples of HBV vaccinated adolescents from the 19 parishes of Kawempe division out of which 149 (51.7%) were males and 139 (48.3%) were females. 26(9.0%) participants had received only the first dose of the HBV vaccine; 45(15.6%) participants had received the first and second doses and 217(75.4%) had received all the three doses of the pentavalent DPT HepB Hib vaccine. Since we had run the Combo test to answer objective one; Participants at exposure (Combo susceptible) to the HBVVI were 221 (76.7%), Acute infections were 4 (1.5%), Participants with Chronic infections were 3 (1.0%), Those that were vaccine protected were 60 (20.8%) that is to say they presented with the surface antibody (HBsAb). To answer objective two, We ran titers of the 60 (20.8%) participants who were vaccine protected that is to say positive for the surface antibody and the results were as follows: Responders were 22 (36.7%) with a titer value above 10IU/L and Non-responders were 43 (66.2%) with a titer value less than 10IU/L. Thus, the prevalence of HBs antibody titer was 36.7% amongst 15-17 year old adolescents at Kawempe division, Kampala Uganda.DISCUSSION: Hepatitis B vaccine 3 dose completion in the study was high at 75.4% and the average age was 16.2 years is accountable on the introduction of the hexavalent HBV vaccine (DTaP, Hib-Hep B) birth dose in Uganda with a schedule of 0 weeks, 6 weeks and 10 weeks as emphasized by the ministry of health since its introduction in 2002 under the Uganda National Expanded Programme on Immunisation, This relatively compares with that showed in African settings of 76% (5) and East Africa (79%). The study revealed that 76.7% of the study participants were combo susceptible/exposed (had no HBV vaccine protection). However, these results are not in agreement with a study by Ocan et al who reported that 0.7% of these persons had active HBVI, 2.3% were confirmed positive for HBsAg; 88.7% had detectable HBsAb; 2.3% represented with HBeAg; A percentage of 4% had positive HBeAb and 17.7% suffered from positive HBcAb (9).the high prevalence of exposure could have been due to coinfections forexample HIV/AIDS patients who had both HBV and HCV (15), HBV and Inflammatory Bowell Disease (IBD) (12), H.I.V/AIDs/HBV, HDV/HBV (16), T.B/HBV (17), HBV/Diabetes (18). Another reason as to why the prevalence of HBV exposure was low in Ocan et al’s study was because the participants he used in his study might have received an HBV booster dose. The prevalence of acute and chronic infections in our study was 1.5% and 1.0% respectively and these findings did not differ much with those of Ocan et al’s study conducted among health workers in northern Uganda in 2022 that reported 0.7% active HBVI and 2.3% were confirmed positive for HBsAg (9). Although most HBV infections are known to occur during infancy through perinatal or early childhood exposure, Risk of infection begins to rise again at adolescence (2). Reasons for the increase in HBV infection are thought to be due to beginning of sexual activity (many adolescents have multiple sexual partners) as well as involvement in risky socio-behavioural activities (body piercings and tattooing), Including drug abuse (sharing needles while injecting drugs into each other’s body) (2).Our study recorded a low prevalence at 33.8% protective levels of vaccine-specific anti-HBs antibody titers amongst 15–17-year-old adolescents in Kawempe division, Kampala-Uganda. This low proportion has also been witnessed in other studies that proved that the HBV vaccine specific antibody concentrations significantly declined 13–15 years following vaccination at birth (6). This could be due to the fact that genetics of individuals differ.The non-responsiveness among the 15-17-year-old adolescents was moderately high at 66.2% amongst vaccinated recipients. This was seen in some studies whereby induced anti-HBS titers underwent a gradual decline that led to decay below the protective level (6). This may also be a result of genetics. LIMITATIONS:We were unable to process more samples because we used specimen archives. CONCLUSIONS :We report an HBV Combo test-based susceptibility of 79.2% and the prevalence of antibody titers was 33.8% among 15-17-year-olds in Kawempe Division, Kampala. Prevalence of acute and chronic infection was 1.5% and 1.0%RECOMMENDATIONS:We recommend that emphasis on monitoring and follow-up of those individuals who did not complete the three-dose schedule of the HBV vaccine. We highly recommend that a booster dose of the HBV Vaccine be administered to adolescents since most of them lack protective antibody titers.We recommend further studies at the national level to validate these results from the Kawempe Division, Kampala.