Study: Patients with flu-associated pneumonia less likely to have been vaccinated
Seasonal flu epidemics cause over 200,000 hospitalizations and between 3,000 and 49,000 deaths annually in the U.S. While pneumonia is the leading infectious cause of hospitalization and death, and is a common serious complication of influenza, the article said evidence in the study that is linked to whether flu shots can lower the risk of flu-associated hospital admissions for contagious pneumonia remains unclear.
The study was performed by Dr. Carlos Grijalva of Vanderbilt University’s School of Medicine in Nashville, Tennessee, after observing patients at four U.S. health facilities between January 2010 and June 2012. Exercising controls for various factors, doctors calculated odds ratios, comparing data from influenza patients who had received flu vaccinations with those with pneumonia, but without the flu.
Of 2,767 patients hospitalized for pneumonia, 162 had laboratory-confirmed influenza; 28, had influenza-associated pneumonia and 766 out of 2,605 control subjects with influenza-negative pneumonia had been vaccinated.
The vaccine's effectiveness was estimated to be 57 percent, meaning that the odds of influenza vaccination among cases hospitalized with influenza-associated pneumonia was 57 percent lower than among non-influenza pneumonia controls.
The authors said the estimated odds ratio and derived vaccine effectiveness from this study could inform subsequent estimates of the national hospitalizations for pneumonia averted by influenza vaccination.
The study was funded by the Influenza Division in the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention.
To access the report on the study: www.eurekalert.org/pub_releases/2015-10/tjnj-pwf100215.php.