Quadruple dose of influenza vaccine may offer HIV patients better protection

HIV-infected patients who received a quadruple dose of seasonal influenza vaccine had a higher antibody response and greater seroconversion rate than did those who received a standard dose, with similar rates of adverse events, a study found.

Researchers conducted a randomized, double-blind, controlled trial at the Hospital of the University of Pennsylvania in Philadelphia from October 2010 to March 2011. In the study, 190 adults with HIV were randomly assigned to receive either a standard dose (15 μg of antigen per strain, n=93) or a high dose (60 μg/strain, n=97) of the influenza trivalent vaccine. Seroprotection was defined as antibody titers of 1:40 or greater on the hemagglutination inhibition assay 21 to 28 days after vaccination.

Results appeared in the Jan. 1 Annals of Internal Medicine.

Seroprotection rates after vaccination were higher in the high-dose group for three strains of flu: H1N1 (96% vs. 87%; treatment difference, 9 percentage points; 95% CI, 1 to 17 percentage points; P=0.029), H3N2 (96% vs. 92%; treatment difference, 3 percentage points; 95% CI, −3 to 10 percentage points; P=0.32), and influenza B (91% vs. 80%; treatment difference, 11 percentage points; 95% CI, 1 to 21 percentage points; P=0.030).

There was no significant difference in the local or systemic reactions between the two groups and no serious adverse events related to vaccine administration. The most frequent local adverse events were pain and tenderness at the injection site. The most frequent systemic adverse effect was myalgia, followed by malaise and headache. However, although seroprotection rates were increased with a higher vaccine dose, researchers noted that their study did not assess the effectiveness of the vaccine in preventing clinical influenza, which would require more study participants.

“A strategy with a single HD [high-dose] immunization is much easier to implement than a multiple-dose schedule,” the authors wrote. “Although a higher dose is 1 route to the protection of this vulnerable population, other strategies may also be explored in the future, such as alternative vaccines, the use of adjuvants, or new schedule strategies.”