Assessment of The Immunization Status of Individuals Vaccinated By Hepatitis B Virus Vaccine In Khartoum State

Abstract

Background: Hepatitis B virus (HBV) is widely distributed all over the world. Quite a large number of the population worldwide is exposed to the virus. It is estimated that 378 million are chronically infected and at risk of developing serious complications like liver cirrhosis and hepatocelluar carcinoma leading to death. Fortunately, an effective vaccine has been introduced to prevent infection with the virus. The rate of infection by HBV has been effectively reduced by universal vaccination with that vaccine. Post-vaccination concentration of vaccine induced neutralizing antibodies against HBsAg above 10 mlU is considered protective against the virus.
Objectives: To assess the state of immunization of Sudanese individuals previously vaccinated by HBV vaccine in Khartoum State.
Methodology: A total of 90 individuals previously vaccinated with HBV vaccine and 70 unvaccinated persons (control) had their blood tested anti-HBsAg. Specimens negative for anti-HBs Ag were further tested for total (IgM & IgG) anti-HBcAg and HBsAg by ELISA. Specimens positive for total anti- HBcAg were further tested for IgM anti-HBcAg.
Results: The majority 76(88.4%) of the vaccinated subjects and 4.28% of the control were found to be positive for anti-HBsAg. Out of the 76 subjects with positive antibody response; 68.4% showed good antibody response (protected against the virus). The remaining (31.6%) showed low antibody response and are therefore at risk of infection. In general 42.2% of the vaccinated subjects and all the control group revealed low or no antibody response and are at risk of infection. The results of this study showed statistically significant difference in the antibody response between those who received three vaccine doses (72.7%) and one dose (18.8%) with P value < 0.05. Two (2.22%) of the vaccinated subjects have developed HBV infection, compared to four (5.71%) of the control group.
Conclusion: Antibody response to HBV vaccine was found 88.4% of the vaccinated subjects, however, considerable number of the vaccinated subjects revealed low or no antibody response. Individuals, who received three doses of the vaccine, had statistically significant antibody response than those who received only one dose.

Keywords: Hepatitis B vaccine, Immunization, IgG, IgM.