Immune Response to Standard Hepatitis B Vaccination in HIV-Infected Patients

Abstract

Due to the similar routes of transmission and risk factors, the rate of human immunodeficiency virus (HIV) and hepatitis B virus (HBV) co-infection is considerable [1-3]. Chronic HBV infection affects approximately 10% of HIV-infected subjects throughout the world, with higher rates in high HBV endemicity areas and in high risk groups such as injecting drug users [2-4]. HBV infection progresses more rapidly in HIVinfected patients, with higher rates of HBV viremia, HBV reactivation, cirrhosis and hepatocellular carcinoma [5]. HBV infection has been also associated with more rapid progression of HIV infection to AIDS, by an increased expression of HIVinfected cells and a faster decrease in CD4 lymphocytes [6,7]. Moreover, the risk of hepatotoxicity from highly active antiretroviral therapy (HAART) increases in HIV/HBV coinfected patients [4, 8]. Therefore according to the current guidelines, HBV vaccine is highly recommended to all asymptomatic HIV-infected patients without evidence of prior HBV infection or the immunity to HBV, [9, 10]. In healthy adults, HBV vaccination is associated with a good protection against HBV infection and has a seroconversion rate of more than 90% [11, 12]. Due to the impaired immune responses, the success rate of HBV vaccination is lower in HIV-infected cases compared to the general population, with immunogenicity rates varying from 17.5% to 72% [13-15]. The risk factors for lower rate of responses to HBV vaccine included higher HIV viral load, hepatitis C virus antibody (anti-HCV) positivity and lower CD4 cell count prior to the vaccination [14, 16-19]. Meanwhile, achieving seroprotection rates of HBV vaccine in HIV-infected patients remains a challenge. Due to the importance of HBV prophylaxis in highrisk groups, particularly HIV infected patients; we aimed to determine the immune responses to standard HBV vaccination in HIV-infected patients and its relation to different variables such as age, sex, route of HIV acquisition and the immune status.