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Vanderbilt researchers work to balance flu vaccine debate

Apr. 4, 2013, 8:49 AM

Research in the last two years to examine the effectiveness of the influenza vaccine has raised public doubt about the flu shot’s effectiveness. But two Vanderbilt researchers co-wrote an editorial in the Journal of the American Medical Association (JAMA)recently to help balance the current debate.

Thomas Talbot, M.D., MPH, and Keipp Talbot, M.D., MPH, are helping to address misconceptions surrounding the annual influenza vaccine’s effectiveness. (photo by Joe Howell)

H. Keipp Talbot, M.D., MPH, assistant professor of Medicine, and her husband, Vanderbilt University Hospital Epidemiologist Thomas Talbot M.D., MPH, associate professor of Medicine and Preventive Medicine, were invited to address the myths and facts about the effectiveness of the annual influenza vaccine.

The editorial was in part a response to broad media coverage of a Centers for Disease Control and Prevention (CDC) report which stated that during the 2012-13 flu season the vaccine against the influenza A (H3N2) virus was only about 9 percent effective against all medically attended visits for people over age 65.

“After the CDC report, even my father called and said ‘Can I stop getting the flu vaccine since it doesn’t work?’ It’s hard because the flu vaccine was indicated in the 1960s for older adults without any clinical trials in older adults, so there are many questions, but we have a number of years of evidence that reinforces the flu vaccine prevents severe disease,” Keipp Talbot said.

The CDC report built on concerns sparked by a research review in The Lancet in October 2011 showing randomized controlled trials (RCT) of influenza vaccine confirmed only about 59 percent effectiveness in adults. No RCTs were found in adults over age 65 or children age 2 to 17. In the JAMA editorial, the Talbots acknowledge this weakness in the evidence, but they point out the influenza vaccine is held to an unrealistically high expectation.

“A prevention measure that reduced the risk of serious outcome by nearly 60 percent in most instances would be a noted achievement; yet for influenza vaccine, it is seen as a ‘failure,’” they wrote.

Tom Talbot has authored numerous publications supporting the vaccination of health care providers against the flu, and Keipp Talbot has authored several about the vaccine’s ability to prevent hospitalization in older adults. Her most recent research, released online Feb. 28 in the journal Clinical Infectious Diseases, showed the flu vaccine was 71 percent effective in preventing the hospitalization of adults over age 50.

Keipp Talbot says this adds to long-standing evidence that the influenza vaccine keeps older adults out of the hospital, but she says it’s just not possible to alleviate all the questions about the vaccine’s effectiveness. To do that, a gold-standard randomized and controlled trial would be required, something she says will never happen because a placebo would have to be used, leaving some people at risk.

“It’s not ethical. We’ve been giving flu vaccine for 52 years. We’re not about to withhold it,” she said.

But newer, and hopefully better, influenza vaccines are in development now. Dorothy Jones and her husband, Walter Reed, have been participating in a study Talbot is leading to test a higher dose influenza vaccine in older adults. Jones says the couple is glad to help sort out the questions.

“We’ve been through the measles and polio. We can remember when polio was crippling, and we lived through that. I believe in the shots,” Jones said.

Vanderbilt is leading the way to help provide a clearer picture. Several flu vaccine research projects are under way, including Keipp Talbot’s research on the double-strength flu shot for older adults, which may be complete in the next year or two. Next year there will be an extra vaccine strain added to some shots and to all nasal spray vaccines, making the current trivalent influenza vaccine quadravalent, potentially adding to its effectiveness.

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