How successful is influenza vaccination in HIV infected patients? Results from an influenza A(H1N1)pdm09 vaccine study

Abstract Aim To determine immune response after single vaccination with AS03-adjuvanted pandemic H1N1 vaccine in HIV-infected patients. Background Individuals living with human immunodeficiency virus (HIV) are at risk with influenza due to hyporesponsiveness to influenza vaccine and a higher probability for developing severe disease. Especially, immunogenicity and tolerability of adjuvanted influenza vaccines in a pandemic setting are not well characterized in HIV infected individuals. Methods Immune response following vaccination with a single dose of influenza A (H1N1)pdm09 AS03-adjuvanted vaccine (H1N1pdm09 vaccine) containing 3.75 μg hemagglutinin was evaluated in HIV infected individuals by hemagglutination inhibition assay. Tolerability was assessed by questionnaires. Results Three hundred eighty-nine patients from two German HIV clinics were evaluated. Seroprotection was found in as much as 191/389 (49%) of patients before vaccination. Following vaccination with H1N1pdm09 vaccine seroprotection rate increased to 66% (257/389). Due to high pre-vaccination seroprotection rates seroconversion was only found in a total of 27/389 (7%) of HIV patients. There was no association of seroprotection/seroconversion and current CD4 + T-cell count, HIV-RNA load in plasma, antiretroviral treatment or demographic factors such as gender, age and ethnicity. The vaccine was overall well tolerated. Conclusions In this large cohort of HIV infected patients with high baseline H1N1 seroprotective titers only a moderate antibody response to a single vaccination with H1N1pdm09 AS03-adjuvanted vaccine was detected. Emerging influenza pandemics warrant usage of booster vaccinations in order to achieve higher immunogenicity to protect a vulnerable patient population such as HIV positive individuals against influenza.