Influenza can be deadly to the elderly.

Compounding the issue? Immune responses to flu vaccines decline with age. So researchers from Brown University conducted a large, randomized clinical trial to see if a flu vaccine with four times the antigen of a standard vaccine had a strengthened effect on seniors over 65.

The results, published in Lancet Respiratory Medicine, were positive. Those given the amped-up vaccination, Fluzone, saw a reduced risk of hospitalization due to respiratory-related illness.

Lead author Dr. Stefan Gravenstein, a professor at both the Warren Alpert Medical School and the School of Public Health at Brown University, said in a university statement that while a prior study showed that older individuals could respond better to the high-dose vaccine, that study focused on relatively healthy older adults.

Gravenstein explained his study established that it would help even the frailest folks, such as those who reside in nursing homes. “In our study, a quarter of the sample was over 90. So we asked if the high-dose vaccine also would work better than regular-dose vaccine in the population we consider least able to respond,” he said. “This paper says yes, it can.”

The research team compared hospitalization rates among more than 38,000 residents of 823 nursing homes in 38 states during the 2013-14 flu season based on Medicare claims data. Just under half the homes, 409 to be exact, administered the high-dose vaccine while the other 414 provided a standard dose.

Hospitalization rates for respiratory illnesses among high-dose patients was 3.4 percent compared to 3.8 percent among standard-dose patients six months after vaccination. In addition, results showed the rate of hospitalization for any reason, respiratory or otherwise, was significantly lower in the high-dose group.

“Respiratory illness as the primary reason for hospitalization accounted for only about a third of the reduction in hospitalization that we measured,” said Gravenstein, who is also affiliated with the Providence Veterans Affairs Medical Center and is an adjunct professor of medicine at Case Western Reserve University. For many patients, the vaccine appeared to help prevent hospitalization for other problems also, including cardiovascular symptoms.

The study did not find a significant difference in the rate of death. However, reducing unnecessary trips to the hospital improves quality of life in elderly patients. 

Sanofi Pasteur provided the vaccine for the study, but was not involved in trial design.