Flu Shot Protects, Even in Years with Antigenic Drift

Inactivated or live attenuated vaccines, as well as school-based shots, protect patients and families

WEDNESDAY, Dec. 13 (HealthDay News) -- Both inactivated and live attenuated influenza vaccines protect adults from the flu, and school-based vaccination programs protect household family members, according to two studies conducted in 2004-2005, a year when flu vaccines were not well-matched to circulating strains. The findings are published in the Dec. 14 issue of the New England Journal of Medicine.

Suzanne E. Ohmit, Dr.P.H., of the University of Michigan School of Public Health in Ann Arbor, and colleagues studied 1,247 patients who randomly received either inactivated or live attenuated influenza vaccines in late 2004. Although most circulating viruses were dissimilar to those included in the vaccine during the ensuing flu season, the researchers found that both types of vaccine prevented influenza A (74 percent), but that live attenuated vaccine was less efficacious for influenza B (40 percent for live attenuated versus 80 percent for inactivated).

James C. King, Jr., M.D., of the University of Maryland in Baltimore, and colleagues identified 11 demographically similar clusters of elementary schools in four states and assigned one school in each to participate in a vaccination program, and one or two schools to act as controls. They found that intervention-school households had significantly fewer influenza-like symptoms and outcomes during a predicted week of peak influenza activity.

"Some have questioned whether the substantial effort to produce and deliver influenza vaccine is justified. The answer is, unambiguously, yes," state the authors of an accompanying editorial. "Indeed, the critical public health question is not whether influenza vaccines should be used, but how they can be used to advantage."

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