MINNEAPOLIS, Oct. 26 (UPI) -- A meta-analysis of studies involving the seasonal flu vaccine found it is effective for 59 percent of adults ages 18-65, U.S. researchers found.
Michael T Osterholm and Nicholas S. Kelley of the University of Minnesota's Center for Infectious Disease Research and Policy, Dr. Alfred Sommer of the Johns Hopkins Bloomberg School of Public Health in Baltimore and Dr. Edward A. Belongia of the Marshfield Clinic Research Foundation in Marshfield, Wis., searched for studies addressing flu vaccine effectiveness from 1967 through last February.
From about 5,700 studies, only 31 studies involving 54,000 people in 23 countries that covered 24 influenza season met their strict criteria, they said.
The meta-analysis, published in Lancet Infectious Diseases found that existing flu vaccines can provide moderate protection from confirmed flu, but its effectiveness is much lower in the young and old.
Pooled evidence from randomized controlled trials showed that standard trivalent inactivated vaccines (seasonal flu) had an effectiveness of 59 percent in those 18-65, but evidence for protection in adults age 65 years or older is lacking, the analysis said.
New vaccines with improved clinical efficacy and effectiveness are needed to further reduce influenza-related morbidity and mortality, the researchers said.