In Adults, Shots Are Best for Flu
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By RONI CARYN RABIN
Published: March 2, 2009
For the best protection against winter flu, adults may just have to roll up their sleeves and take shots the old-fashioned way.
After reviewing the medical records of more than one million members of the United States military over a three-year period, researchers have found that conventional intramuscular shots reduced doctor visits for flulike symptoms by up to 54 percent, while an intranasal vaccine curbed flu-related visits by just 21 percent at best.
The intranasal vaccine, FluMist, is primarily marketed for use in children and is believed to be more effective than the conventional vaccine for them. But FluMist is the only nasal spray flu vaccine approved in the United States, and it is increasingly popular among adults.
The results echo findings from previous studies, which reported that conventional flu shots were more effective in adults. The new study was posted online Monday in The Journal of the American Medical Association.
“Our results are consistent with other studies and data — they’re in the same ballpark,” said Dr. Zhong Wang of the Armed Forces Health Surveillance Center in Silver Spring, Md., who is the primary author of the study.
Military personnel who received flu shots in the 2004-05 flu season had 54.8 percent fewer health care visits for flulike symptoms and pneumonia than those who received no vaccine, 30.7 percent fewer visits the following year and 28.4 fewer visits in 2006-07, the researchers found.
By contrast, those who took the inhaled vaccine had 20.8 fewer visits than the unvaccinated population in 2004-05, 12 percent fewer visits the next year and 10.7 percent fewer visits in 2006-07.
In 2004-05, military personnel who took the inhaled vaccine were actually more likely to end up in the hospital with influenza or pneumonia than those who received no vaccination, the study found.
But the nasal spray was more effective in adults who were being vaccinated against flu for the first time. People in this group had up to one-third fewer health care visits than those who were not vaccinated, the study found.
The new study has limitations, the authors acknowledged. It was not a randomized clinical trial but a weaker look-back study, which used the Defense Medical Surveillance System database to gather health care information about active military personnel ages 17 to 49.
Dr. Chris Ambrose, the director of medical affairs for MedImmune, which makes FluMist, said studies showed that in children it was actually more effective than the conventional vaccine. One study of 4,000 children ages 2 to 5 reported a 54 percent reduction in flu cases among those who received FluMist, compared with those who received the traditional vaccine.
“The important thing to us is that very different results have been seen in children,” Dr. Ambrose said.
The Army has used flu shots since the 1950s to curb the spread of the disease among personnel living in crowded conditions. But FluMist, approved for adults up to age 49, has been gaining in popularity in recent years, and it made up almost half of flu vaccinations among the military personnel studied in the most recent year, up from one-third in 2004-05.