Immunogenicity and safety of trivalent inactivated influenza vaccine in adults living with HIV compared with HIV-uninfected adults: a study from China

Abstract

To evaluate the immunogenicity and safety of trivalent inactivated influenza vaccine (IIV3) in adults aged ≥18 years living with HIV and to provide evidence supporting influenza vaccination in this population in China. This single-center, open-label comparative analysis was derived from a larger three-arm clinical study. For the present comparative analysis, 472 vaccinated participants were planned, including 236 adults living with HIV (Group 1) and 236 age- and sex-comparable HIV-uninfected adults (Group 2). Participants in both groups received one dose of IIV3 (0.5 mL) on Day 0. Blood samples were collected before and 28 days after vaccination for hemagglutination inhibition (HI) antibody testing against A(H1N1), A(H3N2), and B/Victoria strains. Immunogenicity endpoints included seroconversion rate, seroprotection rate, geometric mean titer (GMT), and geometric mean increase (GMI). Safety was assessed by monitoring solicited and unsolicited adverse events (AEs) and serious adverse events (SAEs) during 6 months of follow-up. An unvaccinated cohort of adults living with HIV from the original trial was included only for an exploratory, descriptive analysis of influenza-like illness (ILI), without assessment of vaccine efficacy. A total of 489 participants were enrolled, including 237 in Group 1 and 252 in Group 2. At 28 days post-vaccination, seroconversion rates did not differ significantly between Group 1 and Group 2 for A(H1N1) (91.00% vs. 86.69%, P > 0.05), but significantly lower for A(H3N2) (49.50% vs. 89.52%) and B/Victoria (40.00% vs. 64.52%) (both P  < 0.001). Seroprotection rates were also lower in Group 1 than in Group 2 for A(H1N1), A(H3N2), and B/Victoria (94.00% vs. 97.98%, 63.50% vs. 97.18%, and 40.50% vs. 68.55%, respectively). Post-vaccination GMTs were significantly lower in Group 1 for all three strains (all P  < 0.001). GMI was higher for A(H1N1) but lower for A(H3N2) and B/Victoria in Group 1 than in Group 2 (all P  < 0.001). Multivariable analyses showed that HIV infection remained independently associated with several measures of vaccine-induced immune responses after adjustment for demographic and clinical factors, particularly for A(H3N2). IIV3 was generally safe and well tolerated. Most AEs were mild in severity, and no Grade 4 adverse reactions or vaccine-related SAEs were reported. During the period from 29 days to 6 months after vaccination, few influenza-like illness events were reported among vaccinated and unvaccinated participants living with HIV; these findings were descriptive and were not used to assess vaccine efficacy against influenza. Adults living with HIV developed substantial antibody responses following IIV3 vaccination, although the magnitude of response varied across influenza strains. A(H1N1) seroconversion was high in adults living with HIV, whereas responses to A(H3N2) and B/Victoria were generally lower than those in HIV-uninfected adults. HIV infection remained associated with reduced vaccine-induced immune responses for several strain-specific outcomes after multivariable adjustment, with associations particularly evident for A(H3N2). IIV3 was safe and well tolerated, supporting current recommendations for influenza vaccination in adults living with HIV. https://www.chictr.org.cn/showprojEN.html?proj=255613 , identifier ChiCTR2500112191.