High-Dose Flu Vaccine: Is It Always Better?

By Jane Farrell

People over 65 are often offered a standard vaccine or a high-dose version. But a new study has found that the higher dosage is effective only for people 85 and older.

A new study from the U.S. Department of Veterans Affairs found that for those between age 65 and 84, the standard vaccine works just as well.

The finding was published in the journal Clinical Infectious Diseases.

The investigators looked at more than 165,000 VA patients who got either the regular or high-dose vaccine during the 2010 – 2011 flu season. The study tracked hospitalizations and deaths— indicators of the flu’s more severe impacts.

About 25,000 of the veterans had gotten the high dose, and the rest the standard vaccine.

“The main overall outcome was that we didn’t find a difference between the groups,” says study author Dr. Darren Linkin, with the CDC Prevention Epicenter Program. “But in a secondary analysis, there appeared to be a strong effect for those 85 and older.”

The new findings contrast with those from some other recent studies, although the researchers say some variation may be due to the particular flu seasons that were studied, a VA news release said.

For example, a study just out in The Lancet, funded by the U.S. Food and Drug Administration and focused on Medicare patients, found that the high-dose vaccine was 22 percent more effective at preventing flu-related hospital admissions. The study examined the 2012 – 2013 flu season.

In a study of older adults reported last year in the New England Journal of Medicine, a group with Sanofi Pasteur, the company that makes the high-dose vaccine, found it provided better protection against lab-confirmed flu illness than did the standard vaccine. They also found it triggered stronger immune responses—that is, more antibodies. The two-year trial, which included nearly 32,000 people, stretched from 2011 to 2013.

The FDA study was far larger than VA’s—it included more than 2.5 million U.S. adults. And the Sanofi Pasteur study was a randomized, controlled, blinded trial—the gold standard in clinical research.

Despite those studies, the VA authors say more research is needed to arrive at definitive answers.