Observational study of vaccine effectiveness 20 years after the introduction of universal hepatitis B vaccination in Tunisia.

ABSTRACT

OBJECTIVES: The objectives of this study were to estimate the national prevalence of hepatitis B infection in Tunisia using data from a nationwide survey, to compare results with those obtained in 1996 survey and to evaluate the impact of vaccination twenty years after its introduction. METHODS: A National household-based cross sectional and serological survey was undertaken in 2015 from randomly selected districts using two-stage sampling. Data collection was performed using standardized and pretested questionnaires and collected blood samples were tested for markers of hepatitis B virus infection. RESULTS: National point prevalence of Hepatitis B surface antigen was 1.7% (95% CI [1.6-1.9%]). The highest prevalence was found in the Center and South regions with respectively 2.3% (95% CI [2.0-2.7%]) and 2.2% (95% CI [1.8-2.8%]). Vaccine effectiveness (VE) was 88.6% (95% CI [81.5-93.0%]) and was higher among population aged less than 20 years 96.1% (95% CI [70.1-99.5%]) than those aged more than 20 years 59.0% (95% CI [32.0-75.3%]). VE was 85.6% (95% CI [65.8-93.9%]) is hyper-endemic areas and 89.1% (95% CI [80.3-94.0%]) in meso-endemic and hypo-endemic areas. CONCLUSIONS: The prevalence of Hepatitis B surface antigen decreased compared to previous estimations and classify Tunisia as a low endemic country as result to the introduction of vaccination since 1995.