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| |  Influenza Vaccine Not Fully Protecting Patients With Heart Failure During Flu Season: Presented at HFSA By Jennifer Reising BOSTON -- September 17, 2009 -- Patients with heart failure may require better protection during flu season than the average influenza vaccine can provide, according to study research presented at the 13th Annual Scientific Meeting of the Heart Failure Society of America (HFSA). Researchers measured antibody titres to individual viral strains before vaccination, 2 to 4 weeks after vaccination (during peak levels), and over 6 months after vaccination (post flu season) to determine whether the levels in patients with heart failure would be sustained throughout the influenza season, compared with a control group. "People without heart failure had decreased titre levels throughout the flu season, which we would expect, yet they were above the threshold of protective levels," noted lead investigator Orly Vardeny, PharmD, School of Pharmacy, University of Wisconsin, Madison, Wisconsin, speaking at a poster presentation here on September 14. "However, patients with heart failure decreased below protective levels, which made them more susceptible to influenza. The vaccine wasn't lasting as long as [it was in] the control group, and heart-failure patients weren't being protected against this type of influenza throughout the flu season." Dr. Vardeny's team studied 62 patients with heart failure (18 ischaemic, 44 idiopathic) and 40 healthy control subjects during the 2006-2007 and 2007-2008 influenza seasons. Both groups initially had similar rates of antibody seroprotection (titres >=40 haemagglutination inhibition units [HAU] to >=1 strain). Antibody titres decreased over time in both the patients with heart failure and the control group. The patients with heart failure, however, did not sustain the same levels of seroprotection throughout a 6-month period in both A/H3N2 and A/H1N1 strains. Titres in the A/H3N2 virus showed a greater decrease in the patients with heart failure (peak titre levels of 160 to a postseason level of 30) compared with the healthy control subjects (320 peak titre levels to a postseason level of 60) (P = .004). Antibody titres to the A/H1N1 also fell more in patients with heart failure (peak titre levels of 60 to a postseason level of 30) versus the control group (peak titre levels of 160 to a postseason level of 80 (P = .04) Titres to the B-type strain fell similarly in both groups. The investigators noted that these findings might help explain the reduced efficacy of the influenza vaccine for influenza A -- a more powerful strain. As patients with heart failure are at risk for influenza-related complications, a solution to this problem needs to be determined. "Based on these study findings, there might be some alternative strategies that would better protect people with heart failure against influenza," Dr. Vardeny concluded. "For example, a higher dose of the vaccine might better protect heart failure patients during the whole influenza season, instead of just during the peak season. Or perhaps a booster shot midway through the season might protect these patients more." [Presentation title: Antibody Titers to Influenza Vaccine Wane in Patients With Heart Failure. Abstract 099]
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