CDC refutes reports that influenza vaccine poses risk of developing H1N1

ATLANTA The Centers for Disease Control and Prevention on Wednesday played down recent media reports describing unpublished findings from seasonal influenza vaccine studies conducted in Canada.

The findings from these studies suggest that receiving the 2008-09 seasonal influenza vaccine (which is the vaccine offered last influenza season) was a risk factor for developing influenza caused by the 2009 H1N1 virus. In the studies done in Canada, the increase in risk among persons vaccinated with a seasonal influenza vaccine was approximately double the risk for those who were not vaccinated with seasonal influenza vaccine.

“However, the research findings from Canada have not been published in the medical literature or presented at any public scientific meetings. There has not yet been an opportunity to fully review the studies in detail,” CDC stated.

“Preliminary results of studies conducted in the United States using methods similar to the Canadian studies did not indicate that receiving a seasonal influenza vaccine increased the risk of developing influenza caused by the 2009 H1N1 influenza virus,” the agency added. “No other country has reported that seasonal influenza vaccine increases the risk of developing influenza caused by the 2009 H1N1 influenza virus."

One one study has been published on this issue — an Australian study that did not find any association between receipt of seasonal influenza vaccine and risk of developing influenza caused by the 2009 H1N1 influenza virus.