Background: Although influenza vaccination is recommended in persons infected with HIV-1, its efficacy is unknown.
Objective: To assess the immunogenicity, efficacy, and risks associated with influenza vaccination in persons infected with HIV-1.
Design: Randomized, double-blind, placebo-controlled trial.
Setting: Outpatient military clinic.
Patients: 102 patients with HIV-1 infection.
Intervention: Influenza vaccine (n = 55) or saline placebo (n = 47).
Measurements: Influenza antibody titers, CD4+ cell counts, and plasma HIV-1 RNA levels at baseline, 1 month after immunization, and 3 months after immunization; viral cultures from persons presenting with respiratory illness; and respiratory symptom interview.
Results: Twenty-three placebo recipients (49%) and 16 vaccine recipients (29%) reported respiratory symptoms (P = 0.04). Ten placebo recipients but no vaccine recipients had laboratory-confirmed symptomatic influenza (P < 0.001) (protective efficacy, 100% [95% CI, 73% to 100%]). No effect on plasma HIV-1 RNA levels or CD4+ cell counts was noted.
Conclusion: Influenza vaccination is highly effective in HIV-1-infected persons and does not seem to be associated with substantial changes in viral load or CD4 cell count.