Ask the Experts: Low influenza vaccine effectiveness among older individuals

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CDC reports a vaccine effectiveness of only 27% among individuals 65 years or older for the 2012–13 influenza vaccine.

The 2012–13 influenza vaccine was only 27% effective among individuals 65 years or older, according to findings from a CDC report published in the February 22 Morbidity and Mortality Weekly Report. The agency further noted that vaccine effectiveness (VE) against influenza A subtype H2N3—the most common virus to circulate this flu season—was only 9% in this age group. However, VE against influenza B was considerably better (67%) in patients 65 or older.

These findings were among a wide variety of vaccine topics addressed at the Immunization Update 2013 session on Saturday at APhA2013, the APhA Annual Meeting & Exposition, in Los Angeles.

One of the session's presenters, Stephen Foster, PharmD, Professor at the University of Tennessee and APhA Liaison Representative to the Advisory Committee on Immunization Practices, reported several other salient details to Pharmacy Today:

  • The CDC survey data were based on the U.S. Influenza Vaccine Effectiveness (Flu VE) Network, which consists of five network sites located in Seattle, WA; Marshfield, WI; Ann Arbor, MI; Detroit, MI; and Pittsburgh, PA. The survey was performed among 2,697 children and adults from December 3, 2012, to January 19, 2013.
  • Compared with most influenza seasons, peak influenza activity occurred earlier this season, and the CDC survey was completed before the peak in activity. Overall VE was adjusted for age, site, race, health, and days of illness. The results were reported by age groups and type of influenza virus (total, serotype A, and serotype B).
  • Overall, the vaccination rate for the study population was 43%. VE was calculated to be 56% overall, which is not considerably different from previous flu seasons.
  • Influenza vaccination reduced the risk of outpatient medical visits by 56%.
  • Vaccination remains the most effective method of preventing influenza. Also, vaccination can reduce the severity of influenza disease.
  • Several new influenza vaccines will be introduced to the market next season, including quadrivalent inactive influenza vaccine and live attenuated influenza vaccine, cell-cultured vaccine, and a recombinant hemagglutinin vaccine (FluBlok—Protein Sciences). Trivalent vaccines also will be used next season.

"We know we need a better way to monitor VE and perhaps better vaccines and vaccination strategies," said Foster. "Until then, we can only work to increase vaccination rates and early treatment of influenza with antivirals."

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