(HealthDay News)  HIV-infected adults achieve higher rates of seroprotection when immunized with a high-dose of the influenza trivalent vaccine compared to the standard dose, according to a study published in the Jan. 1 issue of the Annals of Internal Medicine.

Noah McKittrick, MD, from University of Pennsylvania in Philadelphia, and colleagues randomly assigned 190 HIV-infected persons (>18 years) to receive either a standard dose (15mcg of antigen per strain; 93 participants) or a high dose (60mcg/strain; 97 participants) of the influenza trivalent vaccine. The rate of seroprotection was assessed, defined as antibody titers of 1:40 or greater on the hemagglutination inhibition assay 2128 days after vaccination. Seroconversion, defined as a greater than four-fold increase in antibody titers, and the geometric mean antibody titer were also assessed.

The researchers found that, in the high-dose group, seroprotection rates were higher for H1N1 (96% vs. 87%; P=0.029), H3N2 (96% vs. 92%; P=0.32), and influenza B (91% vs. 80%; P=0.03) strains. Both standard- and high-dose vaccines were well tolerated, with the most frequent adverse events being myalgia (19%), malaise (14%), and local pain (10%).

“The implications of this research are important for future vaccination efforts in the HIV-positive population,” the authors write. “This study suggests that a substantial number of HIV-infected patients may not be obtaining sufficient protection with the standard influenza vaccine.”

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