Abstract
IntroductionThe risk of poor vaccine immunogenicity and more severe influenza disease in HIV necessitate strategies to improve vaccine efficacy.MethodsA randomized, multi-centered, controlled, vaccine trial with three parallel groups was conducted at 12 CIHR Canadian HIV Trials Network sites. Three dosing strategies were used in HIV infected adults (18 to 60 years): two standard doses over 28 days, two double doses over 28 days and a single standard dose of influenza vaccine, administered prior to the 2008 influenza season. A trivalent killed split non-adjuvanted influenza vaccine (Fluviral™) was used. Serum hemagglutinin inhibition (HAI) activity for the three influenza strains in the vaccine was measured to assess immunogenicity.Results297 of 298 participants received at least one injection. Baseline CD4 (median 470 cells/µL) and HIV RNA (76% of patients with viral load <50 copies/mL) were similar between groups. 89% were on HAART. The overall immunogenicity of influenza vaccine across time points and the three influenza strains assessed was poor (Range HAI ≥40 = 31–58%). Double dose plus double dose booster slightly increased the proportion achieving HAI titre doubling from baseline for A/Brisbane and B/Florida at weeks 4, 8 and 20 compared to standard vaccine dose. Increased immunogenicity with increased antigen dose and booster dosing was most apparent in participants with unsuppressed HIV RNA at baseline. None of 8 serious adverse events were thought to be immunization-related.ConclusionEven with increased antigen dose and booster dosing, non-adjuvanted influenza vaccine immunogenicity is poor in HIV infected individuals. Alternative influenza vaccines are required in this hyporesponsive population.Trial RegistrationClinicalTrials.gov NCT00764998
Highlights
The risk of poor vaccine immunogenicity and more severe influenza disease in HIV necessitate strategies to improve vaccine efficacy
HIV infection is associated with deficiencies in both humoral and cell-mediated immunity, which can alter the course of common infections and influence vaccine immunogenicity.[1],[2,3,4,5] While highly active antiretroviral therapy (HAART) partially restores these deficiencies, HIV-infected persons remain at increased risk for morbidity from infectious diseases, especially if the ability to generate antigen-specific responses remains impaired.[6]
Vaccine immunogenicity is better in HIV seropositive persons with minimal or no AIDS-related symptoms and high CD4 counts.[14,15,16,17],[18] even in antiretroviral treated HIV patients with high influenza vaccination rates, protection from influenza disease is deficient.[19]
Summary
The risk of poor vaccine immunogenicity and more severe influenza disease in HIV necessitate strategies to improve vaccine efficacy. Controlled trials of single dose inactivated influenza vaccine in HIV-infected adults conducted both in the pre- and post-HAART eras have demonstrated safety but suboptimal antibody response.[2,3][12,13] The likelihood of achieving seroprotective antibodies is poor in those with advanced HIV disease.[7,14,15] Vaccine immunogenicity is better in HIV seropositive persons with minimal or no AIDS-related symptoms and high CD4 counts.[14,15,16,17],[18] even in antiretroviral treated HIV patients with high influenza vaccination rates, protection from influenza disease is deficient.[19] the use of booster dosing and increased vaccine antigen dose have been assessed in the past, the results are conflicting, based on preHAART populations and limited by small sample size.[14,20]
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