Mention the subject of flu vaccination in a group discussion and at least one person will swear that he or she caught the flu from a flu shot. Sorry—that’s not possible. But it is possible—and even expected—that some people will catch the flu despite getting vaccinated because their immune systems need more protection than what a regular flu vaccine can provide, and they may be exposed to a strain not covered by the vaccine. People age 65 and older are particularly vulnerable.

“Older people—those 65 and older—don’t respond as strongly as younger people to any vaccine, including the flu vaccine, because their immune systems simply have become weaker from aging,” said William Schaffner, MD, a professor of preventive medicine and infectious disease specialist at Vanderbilt University School of Medicine. But good news—getting stronger immunity to avoid the flu just became easier for older adults thanks to a new high-dose vaccine that packs more immune-producing antigens into the shot than standard-dose vaccines. The high-dose trivalent vaccine, which protects against three flu strains, became available a few years ago, and research is now showing that it really does deliver in terms of better protection against the flu for older adults.


A two-year research study to track the effectiveness of the new high-dose flu vaccine involved 32,000 men and women age 65 and older. The study participants were randomly assigned to receive either the standard-dose trivalent vaccine or the high-dose trivalent vaccine.

After vaccination, the participants (who didn’t know which vaccine they had received) were instructed to report any illness to the research team. Participants also received weekly or twice weekly phone calls from the researchers from the time they were vaccinated until the end of flu season in April. If a participant came down with flulike symptoms, the research team took a cell swab from inside the nose to see whether the influenza virus was the cause.

At the study’s end, researchers found that the high-dose vaccine was 24% more effective than the standard vaccine in preventing flu in these older adults. This means that among older people who get vaccinated, the new vaccine can keep an additional one-quarter of them from getting the flu. That’s a lot of people!

“The extra protection did come with some extra ‘ouch,’ though,” said Dr. Schaffner. There were slightly more sore arms and short-term fevers after the high-dose vaccine, as the higher dose kicks the immune system in the shorts more briskly!


Among last year’s available flu vaccines was a newly developed type with quadrivalent (four-strain) protection, though it was in scant supply. This year, more standard-dose vaccines will offer quadrivalent protection. The high-dose vaccine, though, will offer only trivalent protection because the manufacturer is, so far, unable to squeeze all the antigen needed for a high-dose quadrivalent vaccine into a syringe that won’t terrify people with its size.

If you are 65 or older, you may now be wondering whether you should get the standard-dose quadrivalent vaccine (for protection from four strains) or the high-dose trivalent vaccine (for extra-strong protection against three strains). Dr. Schaffner recommends the latter. “If you have a choice between the quadrivalent vaccine or the high-dose vaccine, opt for the high-dose vaccine. Although the quadrivalent vaccine has broader protection against flu strains, the high-dose vaccine has been proven, in the two-year study described, to provide more optimal protection against the flu in older people. The same kind of documented proof isn’t yet available for the quadrivalent vaccine,” he said.

If you are concerned about allergic reactions to the flu vaccine, development of a serious neurologic disorder called Guillain-Barré syndrome or the presence of a mercury-based preservative in some vaccines, put your mind at ease with this myth-busting information from Daily Health News.

“Let’s acknowledge that the flu vaccine is good but it’s not perfect,” said Dr. Schaffner. “It’s the best protection we currently have.” Last year’s vaccine prevented between 50% and 60% of potential flu illnesses. The extra protection provided by the high-dose vaccine for people 65 and older boosts that number to 62% to 74%, and that’s a very significant bonus. It may mean the difference between life and death for you or a loved one.