Surgical patients who received the flu vaccine during their hospital stay did not have an increased risk of emergency department visits or subsequent hospitalizations in the week following discharge, compared with surgical patients who did not receive the vaccine. The new study from Kaiser Permanente, published in the Annals of Internal Medicine, also found that compared with unvaccinated surgical patients, vaccinated surgical patients did not have an increased risk of fever nor did they have an increased number of laboratory tests checking for infection.

"Historically, there has been concern among surgeons that vaccinating patients while they are in the hospital can contribute to increased risk of vaccine-related fever or muscle pain, which might be incorrectly attributed to surgical complications," explained Sara Y. Tartof, PhD, MPH, study lead author, Kaiser Permanente Southern California Department of Research & Evaluation. "There have been no data to support that concern. In fact, our study findings show hospital stays are a fine time to vaccinate patients, particularly those who are older and at high risk of complications due to the flu."

The flu is a highly contagious respiratory infection that can cause serious complications, hospitalizations and, in some cases, even death. Some people, such as older adults, young children and people with certain health conditions, are at high risk for serious complications. In addition to recommending annual flu vaccination for people 6 months of age and older, the Centers for Disease Control and Prevention recommends that hospitalized patients who are eligible receive the flu vaccine before discharge.

In this study, researchers analyzed the health records of Kaiser Permanente members in Southern California who were eligible for flu vaccination in the 2010 through 2013 flu seasons. Those seasons were defined as starting Sept. 1 and ending March 31. Of the 81,647 surgeries evaluated, 34 percent involved patients who did not receive the flu vaccine during the flu season, while 8 percent involved patients who had vaccinations during the hospital stay. The remaining surgeries included patients who had vaccine documented either before hospital admission or after discharge from the hospital. Of those surgeries involving patients who were vaccinated during their hospitalization, the majority were vaccinated on the day of discharge (78 percent).

The study was funded through the Vaccine Safety Datalink from the Centers for Disease Control and Prevention. Other authors of the study include Lei Qian, PhD, Lina S. Sy, MPH, Hung Fu Tseng, PhD, Rulin C. Hechter, MD, PhD, and Steven J. Jacobsen, MD, PhD, of the Kaiser Permanente Southern California Department of Research & Evaluation; and Gunter K. Rieg, MD, and Kalvin C. Yu, MD, with the Southern California Permanente Medical Group.