Flu Vaccine May Prevent Flu-Related Pneumonia

Skipping a flu shot may put patients at greater risk for flu-related pneumonia.

Seasonal flu epidemics lead to an estimated average of 226,000 hospitalizations each year. Although pneumonia is a serious flu complication, it is still not understood whether flu vaccines can decrease the risk for related hospitalizations.

“We knew that influenza vaccines could prevent fever and respiratory symptoms associated with influenza infections, but whether influenza vaccines could prevent pneumonia—a more serious complication of influenza infection—was unclear,” Carlos G. Grijalva, MD, MPH, of the Vanderbilt University School of Medicine told Reuters.

However, Dr. Grijalva and her colleagues recently observed that patients admitted to hospitals with influenza-associated pneumonia were less likely to have ever received a flu shot, suggesting that the flu vaccine can prevent related pneumonia.

The researchers observed 2767 children and adults hospitalized for community acquired pneumonia at 4 US sites between January 2010 and June 2012. Of this group, 162 patients had influenza confirmed by laboratory tests, and only 28 (17%) of those influenza-associated pneumonia cases had been vaccinated.

In comparison, 766 (29%) of 2605 control subjects who had pneumonia but tested negative for influenza had been vaccinated.

Therefore, the study authors concluded, “[T]hose with laboratory-confirmed influenza-associated pneumonia, compared with those with pneumonia not associated with influenza, had lower odds of having received influenza vaccination.”

Based on these data, the researchers estimated that influenza vaccine effectiveness was 57%, meaning the pneumonia patients without influenza were about twice as likely to have been vaccinated than those with flu-related pneumonia.

These research findings recently published in JAMA strongly reflect previous research presented at ID Week in October 2013.