Hepatitis B virus infections in apparently healthy urban Nigerians: data from pre-vaccination tests.

BACKGROUND: In spite of the availability of an effective vaccine since 1982 against hepatitis B, infection with hepatitis B virus (HBV), which is 50 to 100 times more infectious than HIV, still persists in most parts of the world with Nigeria being described as an endemic zone. We therefore set out to establish the prevalence of this infection and evaluate its relationship with age and gender in urban Nigerians. METHODOLOGY: During pre-vaccination tests, blood samples were collected by finger-prick and venepuncture from 1,891 subjects aged < or = 60 years, between 2008 and 2009 after having obtained informed consent and ethical clearance. Smart Check HBsAg (Globalemed, Cape Town, South Africa) and ShantestTM-HBsAg Elisa (Shantha Biotechnics Ltd, Hyderabad, India) were used for initial and confirmatory tests respectively. RESULTS: Of the 1,891 participants, 957 (50.6 %) were males and 934 (49.4%) were females. Overall 114 (6.0%) were positive, of whom 71 (7.4%) were males and 43 (4.6%) females. Those aged 21-30 years had the highest infection rate, and males were more likely to be infected with the virus than females (P > 0.05). CONCLUSIONS: Such a high prevalence of a vaccine-preventable infection questions the effectiveness of the Nigerian vaccination strategies. The Nigerian government hepatitis B vaccination programme, which hitherto is limited to the National Childhood Immunisation Programme, should include the adult population.

Evaluation of a recombinant DNA hepatitis B vaccine in a vaccinated Nigerian population.

INTRODUCTION: Recombinant hepatitis B vaccine was introduced in 1986 and has gradually replaced the plasma-derived hepatitis B vaccine. No published data are available on the immunogenicity of hepatitis B vaccines in Nigerians. The current study aimed to evaluate protective sero-conversion rates after vaccination with Shanvac-B rDNA hepatitis B vaccine in Nigerian subjects between January and September 2009. METHODOLOGY:   After having obtained informed consent and ethical clearance, 2 mL of blood were aseptically collected from each participant aged ≤50 years, one month after the first, second and third doses of the vaccine. Sera were separated into cryovials and frozen at -21oC until analysed for the detection of the protective antibody titre induction. Protective antibody titre was defined as a titre of ≥10 mIU/mL. RESULTS: Of the 376 participants, 192 (51.1%) were males and 184 (48.9%) were females. A total of 144 subjects participated in the first-dose group, nine (6.3%) of whom developed protective antibody titre (8.3% of males and 4.2% of females). Of the 121 participants in the second-dose group, 108 (89.3%) developed protective antibody titre (98.3% of males and 80.3% of females), while of the 111 participants in the third-dose group, 100% protectively sero-converted. Males were more likely to develop protective antibody titre than females after the second dose (P < 0.05). CONCLUSION: This data provides additional evidence for the efficacy of Shanvac-B rDNA hepatitis B vaccine and the need to adhere to the recommended three-dose schedule to achieve full and lasting sero-protection among Nigerians.