For Most People, Most of the Time, Flu Shots Are Effective

Tuesday, October 07, 2008

ROCHESTER, Minn.— A flu shot doesn't always prevent the flu. But that's no reason to skip the annual vaccination, according to the October issue of Mayo Clinic Health Letter.

Mayo Clinic doctors recommend an annual flu shot for adults over age 50, except for those with medical conditions such as allergies that could make the vaccine risky. The flu shot also is recommended for those with medical conditions such as heart disease or diabetes or for all others at high risk of complications.

Why the broad recommendation? For most people, most of the time, the flu shot works. An annual shot significantly reduces the odds of catching the flu and can lessen the severity if flu occurs. For higher risk older adults, the flu shot can reduce hospitalizations by up to 70 percent and deaths by more than 80 percent.

However, the vaccine has limitations. Each year, a new flu vaccine is produced to account for recent influenza strain mutations. Research and production is a year-round effort, involving about 180 laboratories around the globe, to determine the most effective formulation for the upcoming flu season.

Despite rigorous analysis, there's no guarantee that the vaccine will be a perfect match for the influenza strains that circulate. The match is effective about 90 percent of the time. So, even with a flu shot, some people get the flu.

But vaccination or not, when flu symptoms first appear — fever, chills, sweating, muscle aches — quickly contact a doctor. When antiviral drugs such as oseltamivir (Tamiflu) or zanamivir (Relenza) are taken within 48 hours after the first signs of the flu, the length of the illness may be reduced by a day or two.

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Mayo Clinic Health Letter is an eight-page monthly newsletter of reliable, accurate and practical information on today's health and medical news. To subscribe, please call (800) 333-9037 (toll-free), extension 9771, or visit www.healthletter.mayoclinic.com.

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