How effective is that flu shot? A new study presented during IDWeek 2015 in San Diego, an annual meeting of health professionals, found that in the elderly, a higher dose better helps to reduce the risk of hospitalization. A group of researchers’ administered a flu shot four times as strong as standard flu shots, and it lowered hospital admission by a little more than one percent; the number dropped from 20.9 percent to 19.7 percent.

This may not seem like a significant drop, but it is. Lead study author Dr. Stefan Gravenstein, director of the Center for Geriatrics and Palliative Care at University Hospitals Case Medical Center, said in a statement that if this higher dose shot was given​ to approximately 1.5 million nursing home residents, it would translate to thousands fewer being hospitalized. The Centers for Disease Control and Prevention reported that the risk of hospitalization is one in five during flu season, a statistic backed up by this study.

Gravenstein's study involved over 50,000 nursing home residents age 65 and older (14,000 were over the age of 90) from 38 different states; the participants were given flu shots for protection between November 2013 and March 2014. Nursing homes were randomly assigned one of two vaccines: the standard vaccine, or the higher dose. The benefit of vaccine has been questioned among older populations before, but this study highlights that a vaccine can still be effective after turning 65.

"Flu in a nursing home population is a major cause of hospitalizations," Gravenstein said. "In addition to pneumonia, flu can contribute to heart attacks, heart failure, and stroked, especially in an older nursing home population where it can easily spread among residents. In our study, for every 83 individuals receiving the high dose vaccine a person was prevented from being hospitalized during the influenza season."

The Advisory Committee on Immunization Practices (ACIP), a group of medical and public health experts that decide recommendations on use of vaccines in the civilian population, will ultimately decide if the higher dose should be a standard practice in nursing homes.

Source: Gravenstein S, Taljaard M, Gozalo P, Dahal R, Davidson E, Han L, et al. Higher Dose Flu Shot Decreases Hospitalization Of Older Nursing Home Residents. Infectious Diseases Society of America Annual Meeting. 2015.