Introduction: The risk of poor vaccine immunogenicity and more severe influenza disease in HIV necessitate strategies to\r\nimprove vaccine efficacy.\r\nMethods: A randomized, multi-centered, controlled, vaccine trial with three parallel groups was conducted at 12 CIHR\r\nCanadian HIV Trials Network sites. Three dosing strategies were used in HIV infected adults (18 to 60 years): two standard\r\ndoses over 28 days, two double doses over 28 days and a single standard dose of influenza vaccine, administered prior to\r\nthe 2008 influenza season. A trivalent killed split non-adjuvanted influenza vaccine (FluviralTM) was used. Serum\r\nhemagglutinin inhibition (HAI) activity for the three influenza strains in the vaccine was measured to assess\r\nimmunogenicity.\r\nResults: 297 of 298 participants received at least one injection. Baseline CD4 (median 470 cells/mL) and HIV RNA (76% of\r\npatients with viral load ,50 copies/mL) were similar between groups. 89% were on HAART. The overall immunogenicity of\r\ninfluenza vaccine across time points and the three influenza strains assessed was poor (Range HAI $40 = 31ââ?¬â??58%). Double\r\ndose plus double dose booster slightly increased the proportion achieving HAI titre doubling from baseline for A/Brisbane\r\nand B/Florida at weeks 4, 8 and 20 compared to standard vaccine dose. Increased immunogenicity with increased antigen\r\ndose and booster dosing was most apparent in participants with unsuppressed HIV RNA at baseline. None of 8 serious\r\nadverse events were thought to be immunization-related.\r\nConclusion: Even with increased antigen dose and booster dosing, non-adjuvanted influenza vaccine immunogenicity is\r\npoor in HIV infected individuals. Alternative influenza vaccines are required in this hyporesponsive population.
Loading....