Study: Getting flu shot 2 years in a row may lower protection
by Robert Roos – News Editor
Center for Infectious Disease Research & Policy
Academic Health Center
University of Minnesota
Experts are puzzled by a new study in which influenza vaccination seemed to provide little or no protection against flu in the 2010-11 season—and in which the only participants who seemed to benefit from the vaccine were those who hadn’t been vaccinated the season before.
The investigators recruited 328 households in Michigan before the flu season started and followed them through the season. Overall, they found that the infection risk was nearly the same in vaccinated and unvaccinated participants, indicating no significant vaccine-induced protection, according to their report in Clinical Infectious Diseases.
An additional finding was that the vaccine did not seem to protect participants who were exposed to flu in their own household, though the numbers in that arm of the study were small.
Researchers from the US Centers for Disease Control and Prevention and the University of Hong Kong collaborated with University of Michigan researchers on the study, with Suzanne E. Ohmit, DrPH, of Michigan as the lead author.
The findings come amid a growing number of studies that raise questions about flu vaccine effectiveness (VE). They include, among others, last week’s CDC report that this year’s vaccine has worked poorly in elderly people and three recent European studies showing that vaccine-induced immunity in the 2011-12 season waned after 3 to 4 months. Other studies have cast doubt on the long-standing belief that a close match between the vaccine virus strains and circulating strains improves VE.
Read the Full Report Here: http://www.cidrap.umn.edu/cidrap/content/influenza/general/news/mar0113vestudy.html