Prevalence and factors associated with characteristics of hepatitis B susceptibility among vaccinated adults in Malaysia: a cross-sectional study.

Hepatitis B vaccination is a cornerstone of global disease prevention, yet susceptibility among vaccinated individuals remains a concern. This study aimed to determine the prevalence and factors associated with hepatitis B susceptibility in vaccinated adults in Malaysia. A cross-sectional analysis was conducted using data from the National Health and Morbidity Survey (NHMS) 2020, involving 4,083 respondents aged 15 years and older. Serological testing for hepatitis B virus (HBV) markers, HBsAg, anti-HBs, and anti-HBc assays was performed. Susceptibility was defined based on serological profiles, and complex sampling logistic regression was employed to identify associated risk factors. Among the participants, 64.9% (2,649/4,083) were susceptible to HBV infection, with a prevalence of 22.9% among vaccinated individuals. Susceptibility was notably higher in young adults aged 15–29 (19.0%), and Malay ethnic group (20.5%). Additionally, individuals with tertiary education (18.9%) and single marital status (20.1%) exhibited elevated susceptibility. Multivariate analysis revealed significant associations with ethnicity, where Chinese (aOR 7.10, 95% CI: 2.67, 18.91) and other ethnic groups (aOR 5.67, 95% CI: 2.03, 15.92) had higher odds of susceptibility compared to Malays. Education level was another strong predictor, with tertiary (aOR 9.82, 95% CI: 3.61, 26.73), secondary (aOR 8.88, 95% CI: 3.42, 23.11), and primary education (aOR 6.96, 95% CI: 2.77, 17.51) showing substantially increased odds relative to no formal education. This study highlights a substantial prevalence of hepatitis B susceptibility among vaccinated adults in Malaysia. Ethnicity and education level emerged as significant factors. These findings underscore the need for targeted interventions, such as booster vaccinations or enhanced screening, particularly for high-risk groups like the Chinese and other minority ethnicities, as well as those with higher education levels. Further research is warranted to explore these associations’ underlying reasons and optimize vaccination strategies in Malaysia.