Evaluation of the immune response to hepatitis b vaccine in different age groups of the population of sana’a-Yemen

الملخص EN

Objectives : The study was made to evaluate the immune response to HBV among individuals with different ages and sexes by measuring the level of circulating anti-HBs antibodies over an interval of 1 to 5 years after immunization with the three doses of hepatitis B vaccine.

Methods : A total of 300 individuals vaccinated against HBV prior to the study were included, of whom males represent 47.7 % and females 52.3 % with a mean age of 26.67 years.

Sera were tested for HBsAg and anti-HBc by qualitative ELISA and anti-HBs by ELISA quantitative technique.

The individual’s data were collected in a pre-designed questionnaire including : vaccination date, number of doses of vaccine, sex, occupation and age at the time of the present study.

Results : Two hundred and sixteen (81.2 %) of 266 individuals (lacking both HBsAg and anti-HBc) responded to the vaccine with anti-HBs antibody level ≥10 mIU / ml.

Thirty-four (11.3 %) of 300 individuals were reactive to anti-HBc, indicating an immune response due to previous infection rather than vaccination.

Seven (2.3 %) of all vaccinated individuals were reactive to HBsAg, indicating infection.

Individuals having ages < 15 years had the highest immune response (89.8 %) with antibody level ≥10 mIU / ml.

There was no difference in response at ages from 16-35 (82.8 %), while the lowest response was obtained at ages > 36 years (66.7 %).

The present study included two vaccination schedules, the first one at 0, 1, 2 months, showing an immune response of 62.2 %, while the second schedule at 0, 1, 6 months showed a greater immune response of 83.1 %.

Individuals immunized with a yeast-derived vaccine had higher anti-HBs levels (81.9 %), than those immunized with a plasma-derived vaccine (79.8 %).

The year intervals (1-5 years) after primary immunization showed no difference in the immune response.

Conclusion : This study revealed a high response rate to the vaccine.

However, a considerable proportion of vaccinated individuals remain to be reconsidered for either revaccination or booster doses due to nonexistent, inadequate, or low response.

The schedule of 0, 1, and 6 months was more efficient in inducing antibodies towards the vaccine than the 0, 1, 2 months schedule.