Hepatitis B Vaccine Nonresponse and Associated Risk Factors: Insights From a Cohort Study.

Hepatitis B virus (HBV) infection remains a critical global health issue, particularly in high-burden regions with substantial global morbidity and mortality. Despite the efficacy of the hepatitis B vaccine in inducing immunity, a subset of vaccinated individuals fails to achieve adequate immunity. This study investigated the factors influencing immunological response to the hepatitis B vaccine among Nigerian adults. A cohort study was conducted at Usmanu Danfodiyo University Teaching Hospital, Sokoto, involving 307 participants aged 19-60 who had not previously received the hepatitis B vaccine. Data were collected using structured questionnaires assessing demographic characteristics, medical history, and lifestyle factors. Participants received GeneVac-B, a recombinant hepatitis B vaccine, and 0-, 1-, and 2-month schedule anti-HB levels were measured post-vaccination using a commercial enzyme-linked immunosorbent assay (ELISA) kit (AccuDiag ELISA, Diagnostic Automation/Cortez Diagnostics, Inc., USA) to classify vaccine response. The association between demographic and lifestyle factors and vaccine response was analyzed using IBM SPSS Statistics (Version 25). Of the 307 participants, 209 received the first vaccine dose, and 192 completed all three doses. Anti-HB quantification revealed that 94.3% of the participants achieved protective immunity (≥ 10 IU/L), while 5.7% were classified as nonresponders (< 10 IU/L). Statistical analysis indicated significant differences in the immune response based on gender (p = 0.031), with females exhibiting higher mean anti-HB levels than males. Negative correlations were observed between age and vaccine response (ρ = -0.296, p < 0.01) and between body mass index (BMI) and response, although the latter was not statistically significant (ρ = -0.131, p = 0.071). Prior tuberculosis, malaria, measles, smoking, and alcohol use showed no significant impact on the immune response, although recurrent malaria, measles, and smoking were associated with slightly lower mean antibody levels. The study indicates gender and age significantly influence hepatitis B vaccine response, with females and younger individuals demonstrating stronger immunity.