March 28, 2013
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Adjuvanted vaccine more effective against some influenza subtypes in older patients

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The AS03 adjuvanted trivalent influenza vaccine was slightly more effective against some subtypes of seasonal influenza compared with a non-adjuvanted vaccine in patients aged at least 65 years, researchers from the Influence65 study group reported.

“Although few vaccine efficacy and effectiveness studies have been done in elderly adults, the substantial burden of influenza in this population despite widespread vaccination suggests that vaccines with increased efficacy are needed,” the researchers wrote in The Lancet Infectious Diseases.

The randomized trial took place in 15 countries during the 2008-2009 and the 2009-2010 influenza seasons. Patients aged at least 65 years received either an AS03-adjuvanted trivalent vaccine or a non-adjuvanted trivalent vaccine. There were 43,802 participants: 21,893 were assigned to the AS03-adjuvanted vaccine and 21,802 were assigned to the non-adjuvanted vaccine.

In the year 1 efficacy cohort, influenza A and influenza B were less common among those who received the AS03-adjuvanted vaccine. The relative efficacy was 12.11% (95% CI, –3.40 to 25.29). Fewer patients who received AS03-adjuvanted vaccine became infected with influenza A: the relative efficacy was 17.53% (95% CI, 1.55-30.92). Fewer patients also developed influenza A H3N2: The relative efficacy for the adjuvanted vaccine was 22% (95% CI, 5.68-35.49).

“Our study suggests that the benefit of influenza vaccination in elderly people might vary depending on influenza subtypes,” the researchers wrote. “Although findings for our primary endpoint were not significant, our trial had 43,000 elderly participants in stable health and provides valuable lessons for assessment of new influenza vaccines in this population.”

Disclosure: Several researchers are employees of GlaxoSmithKline. Other researchers report financial relationships with Abbott Pharmaceuticals, GlaxoSmithKline, MedImmune, Novartis and Sanofi-Pasteur.