Immunization against Hepatitis B Virus: Serological Status of West African Populations Residing in Cotonou (Benin) and Dakar (Senegal)

Abstract

Background: According to WHO estimates, by 2022 over 296 million people are living with chronic hepatitis B virus (HBV) infection, and over 820,000 have died from complications. In sub-Saharan African countries such as Benin and Senegal, few research studies have addressed the issue of HBV immunization. Objective: The main objective of this study was to evaluate immunization against the hepatitis B virus in populations residing in Cotonou and Dakar by titrating anti-HBs antibodies (Ab) and detecting total anti-HBc immunoglobulins (Ig). Materials and Methods: This was a prospective, descriptive, analytical study of two West African populations recruited in Dakar at the Laboratory of Medical Biology (LBM) of the General Hospital Idrissa Pouye (HOGIP) and in Cotonou at the LBMs of the health centres of the Cotonou archdiocese. HBsAg-negative patients constituted our study population. The study took place in November-December 2019 for Dakar and February-March 2020 for Cotonou. Anti-HBs antibodies were tested and titrated. In the event of anti-HBs positivity, total anti-HBc was determined. A microparticle chemiluminescence immunoassay was used for marker determination. The detection threshold was 2.50 IU/L for anti-HBs. Excel and IBM SPSS Statistics software were used for data analysis. Subjects ’ sociodemographic characteristics were collected using a questionnaire, as was knowledge of their vaccination status. The study was approved by the ethics committees in Benin and Senegal. Results: A total of 394 HBs antigen-negative participants were recruited: 205 in Cotonou and 189 in Dakar. The population was predominantly female, with 65.36% (N = 134) and 57.14% (N = 108) women in Cotonou and Dakar respectively. The median age of participants was 29 years in Cotonou, with extremes of 10 and 65 years, versus 39 years in Dakar, with extremes of 6 and 93 years. Some participants claimed to be unaware of their vaccination status: 33.17% in Cotonou and 56.61% in Dakar. The total prevalence of anti-HBs-positive subjects was 88.78% (N = 182) in Cotonou and 98.41% (N = 186) in Dakar. In Cotonou (N = 205), 35.61% (N = 73) of subjects had protective anti-HBs levels between 11.60 IU/L and 10,000 IU/L. In Dakar, 61.38% (N = 116) of subjects had protective HBV immunity, with anti-HBs titres ranging from 10.30 IU/L to 11357 IU/L. In Cotonou, 80.82% (N = 59) of immunized subjects (N = 73) had anti-HBC antibodies, compared with 84.48% (N = 98) of immunized individuals (N = 116) in the population recruited in Dakar, indicating immunization following HBV infection. Conclusion: Our study involved a predominantly female population, many of whom were unaware of their serological status. Vaccination policies and knowledge of the viral hepatitis B epidemic need to be strengthened.