ABSTRACT
BACKGROUND: Hepatitis B (HB) vaccine represents one of the major achievements in the 20th century. The most important epidemiologic factor affecting the chronic carrier rate is age of infection. The earlier in life an infection occurs, the higher the probability that this infection will result in chronic carriage. METHODS: A seroepidemiologic study was conducted to examine the impact of HB vaccination on the carrier state among a vaccinated group of children (1000) compared to a non-vaccinated group (500) aged 6 years in Alexandria, Egypt. RESULTS: The rate of HbsAg positivity among the vaccinated group was found to be 0.8% compared to 2.2% among the non-vaccinated group. The study showed that the efficacy of HB vaccine in preventing the carriage of HbsAg, 5 years after full course vaccination, was estimated to be around 67%. However, long-term monitoring should continue to confirm the efficacy of the vaccine in preventing chronic carrier state. On the other hand, studying the exposure to some risk factors associated with hepatitis B virus (HBV) infection revealed more or less a similar pattern of exposure among both vaccinated and unvaccinated children. CONCLUSION: It can be concluded that the significantly lower rate of HbsAg positivity among the vaccinated compared to the rate among the non-vaccinated is attributed to the preventive effect of the vaccine.
