Liver related cancer and cirrhosis mortality rates have been reduced globally by the Hepatitis B vaccine however decay still happens. We aimed at determining the prevalence of breakthrough HBV infections (Exposure, Acute and chronic infections) and the prevalence of protective levels of vaccine specific antiHBs antibody titers amongst 15–17-yearold adolescents in Kawempe division, Kampala, Uganda. A cross sectional study . Sample size: 288 participants. The results showed; Males; 149 (51.7%), Females; 139 (48.3%). First dose recipients; 26 (9.0%) , Second dose recipients; 45 (15.6%) and Third dose recipients; 217 (75.4%).Combo test results: Participants at exposure (Combo susceptible);221 (76.7%), Acute infections; 4 (1.5%), Chronic infections; 3 (1.0%) and vaccine protected 60 (20.8%).Titer test results: Responders ; 22 (36.7%) and non-responders were 43 (66.2%). In conclusion: Hepatitis B vaccine 3 dose coverage was good at 75.4% . The study revealed an exposure rate of 76.7% for adolescents who had primarily been vaccinated owing this to genetics, Storage, Usage of overdue medicines and in-completion of HBV doses. The prevalence of acute and chronic infections in our study was moderately high at 1.5% and 1.0%. Our study recorded a low prevalence of protective anti-body titers at 33.8% possibly due to genetics.

Miss Nambafu Joan graduated with a bachelor’s degree in science technology- biology from Kyambogo University in 2015.She later enrolled and completed her master of science in immunology and clinical microbiology from Makerere University in 2025.She is currently a PHD student at Makerere University. She is an author and co-author.