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Annual flu shots are effective in preventing infection, onset of respiratory illness and may reduce work absences, according to an article in the March 10 issue of The Journal of the American Medical Association (JAMA).

James A. Wilde, M.D., formerly of Case Western Reserve University School of Medicine in Cleveland, and colleagues studied 264 young health care professionals (HCP, mean age 28.4 years) without chronic medical problems at two teaching hospitals in Baltimore to determine the effectiveness of an influenza (flu) vaccine in reducing infection, illness and absence from work. Wilde is now at the Medical College of Georgia in Augusta. This is the first study in HCP to assess the effect of influenza vaccine in a randomized, double-blind controlled trial over three successive flu epidemic seasons, according to the researchers.

The researchers report that the flu vaccine was 88 percent effective in preventing influenza type A infection and 89 percent effective in preventing influenza type B infection, compared to the placebo group. Health care workers who received the flu vaccine during two consecutive flu seasons and first-time flu vaccine recipients became infected with influenza at much lower rates (2.3 percent and 1.5 percent, respectively) than those in the control group who received the a placebo vaccine in consecutive flu seasons or once (15 percent and 13.6 percent, respectively).

The researchers also report that the flu vaccine reduced the number of days absent from work by 53 percent and reduced the number of days of respiratory illness accompanied by fever by 29 percent.

“Our data show a 14 percent risk of developing influenza type A or B infection for the individual health care professional who remains unvaccinated and show that influenza infection will increase the risk of experiencing a febrile respiratory illness [respiratory illness accompanied by fever] or work absence by four-fold,” the researchers write. “Moreover, among subjects in our study, influenza infection was associated with experiencing an additional 1.5 days of febrile respiratory illness and 0.5 days of absence from work.”