A new analysis finds that the flu vaccine provides only moderate protection against the flu, noting that such protection is greatly reduced or absent during some flu seasons.
The analysis is published in The Lancet., and reported on WebMD.
"While the vaccine does work, and we still recommend that it be used, it does not demonstrate the kind of efficacy that has often been reported," study researcher Michael T. Osterholm, MD, of the University of Minnesota Center for Infectious Disease Research and Policy, told WebMD.
The researchers screened 5,700 articles and studies, identifying just 31 that used highly specific diagnostic testing to confirm influenza.
Their review of these studies showed that the trivalent inactivated vaccine (TIV) -- which accounts for about 90% of flu vaccines given in the U.S. -- had 59% effectiveness in healthy adults between the ages of 18 and 65.
Nasal Spray Vaccine for Children
Ten studies examined the nasal spray flu vaccine in children between the ages of 6 months and 7 years, finding it was effective for of 83% of that group., reports WebMD.
The nasal vaccine is approved for use in healthy people ages 2 to 49.
Osterholm tells WebMD that the impressive protection should convince vaccine policy makers to recommend the nasal spray flu vaccine over the injected TIV vaccine in children.
"The [nasal spray flu vaccine] works very well in children, but it has never been preferentially recommended," he says. "We could potentially have a much greater impact in preventing influenza if we were to encourage the use of [the nasal spray flu vaccine] in that group."
