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Good mood may make a flu shot more effective, study finds

by Linda Carroll / / Source: TODAY

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Here's something to keep in mind as the U.S. braces for a potentially bad flu season: Being in a good mood on the day you get your flu shot may boost the effectiveness of the vaccine, a new study suggests.

British researchers said they decided to investigate factors that might affect how the body reacts to the vaccine in older adults because the flu shot is only effective in 17 to 53 percent of people over age 65.

It’s not clear exactly how mood might impact the efficacy of the vaccine, but it’s possible that certain stress hormones might be involved, said the study’s lead author Kieran Ayling, a researcher at the University of Nottingham.

How big of a role did mood play?

“One way to understand the size of the effect is to look at the percentage of people who reached levels of flu antibodies that were likely to provide protection,” Ayling said. “In this case, for those with positive mood scores in the top half of our sample on the day of the vaccination, 63 percent had protective levels to the H1N1 strain at 16 weeks after vaccination, compared to 38 percent of those with positive mood scores in the lower half.”

To look at what issues might influence the efficacy of flu shots in older adults, Ayling and his colleagues asked 138 volunteers between the ages of 65 and 85 to fill out questionnaires detailing health, demographic and lifestyle factors, and mood. Each volunteer’s antibody levels to various flu strains were also measured at the outset.

During the 16 weeks of the study, researchers asked the volunteers to keep track of diet, sleep and exercise levels. The volunteers were also asked to keep a daily diary detailing their moods.

At four weeks and 16 weeks after the flu vaccination, the researchers measured flu blood antibody levels in each volunteer.

When the researchers analyzed their data, they determined that the only factor that appeared to predict how well the flu shot worked was mood.

Ayling isn’t ready to extend the findings beyond the age group studied by the researchers. “Older adults’ immune systems are somewhat less effective due to a natural aging process, which affects many different immune cells and processes,” he explained.

Different processes may be going on in younger people who have immune problems, Ayling added.

What to keep in mind:

For those who want to improve the chances of having the flu shot be effective, Ayling suggested “people could engage in something they find enjoyable before going for their vaccination, for example seeing the grand kids or watching a favorite comedy. Alternatively they might want to avoid those things they know would put them in a bad mood.”

Dr. Michael Ison, an infectious disease expert unaffiliated with the new study, cautioned that the wrong message to take from the new study would be to put off having a flu shot until you’re in a good mood.

“I would hate to see someone who was anxious or unhappy not get the flu shot when it is offered,” said Ison, a professor in the division of infectious disease and organ transplantation at Northwestern University’s Feinberg School of Medicine.

Ison said he’d like to see more studies before recommending his patients change their behavior in any way. It’s entirely possible, Ison said, that positive mood could be a marker for some other factor that is making the flu shot more effective in some people.

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