The weird way you can make your flu shot more effective

In a good mood? It might be time to get your flu shot.

Getting the vaccine when you’re in a positive state of mind may increase its ability to help you fend off the illness, according to new research.

The study, which was published in the journal Brain, Behavior, and Immunity, observed 138 people over a six-week period when they were set to get their flu shot. Researchers quizzed the study participants three times a week on their moods, physical activity levels, diet, and sleep habits to try to determine whether psychological and behavioral factors can influence how well a person’s body responds to the flu vaccine. They then measured the amount of influenza antibody each person had in their blood at four weeks and 16 weeks after they had the shot.

Of all of things they measured, the researchers found that only having a positive mood over the six-week period affected how well the shot worked. Namely, people who were more positive had higher levels of the influenza antibody, which helps to fight off the illness, in their body after receiving the shot. Being upbeat on the day of the shot helped too: Scientists found that people who were positive right before the injection had between 8 and 14 percent more antibody in their blood than their less-sunny counterparts.

The study didn’t look at why this happens, but study co-author Kavita Vedhara, PhD, a professor of health psychology at the University of Nottingham, tells Yahoo Lifestyle that she has a few theories. One is that positive people tend to have healthier lifestyles, which would be good for their immune systems.

Having a positive mood might also alter the levels of hormones like the stress hormone cortisol and influence your autonomic system and its release of adrenaline and noradrenaline. “All of these communicate directly with the immune system, making it more or less effective and in turn impacting on how well the vaccination works,” she explains. It’s also possible that a positive mood acts as a “buffer” against the effects of being in a bad mood, which has a harmful impact on your immune system.

Vedhara’s study found that having a positive mood over the full six weeks as well as on the day of the shot caused people to produce higher levels of the antibody after they were vaccinated. “But the intriguing finding was that the day of vaccination effect appeared to be stronger,” she says. “This suggests to us that perhaps even short-term improvements in mood could have beneficial effects — and we certainly know that the immune system can be altered by even short-term changes in mood.”

While it’s great to be in a good mood when you get your shot, Vedhara says that the effects are likely to be more pronounced in old people, who don’t usually respond as well to the flu vaccine as young people. (The vaccine is estimated to only be effective in 17 to 53 percent of older adults compared with 70 to 90 percent of younger people.) Still, when it comes to fending off the flu, every little bit helps.

Read more from Yahoo Lifestyle:

• The bad habit that makes you 4 times more likely to catch a cold

• Body-positive blogger wishes she could hug the people who laugh at her

• Musician won’t hide psoriasis anymore: ‘I don’t feel beautiful yet, but I do feel braver’

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