Researchers at the University of Nottingham, UK, found that a positive mood has a major impact on the effectiveness of the flu jab than diet, sleep, and exercise.

Health experts estimate that the flu vaccine is effective in only 17 to 53 percent of cases in older adults compared to 70 to 90 percent effectiveness for younger patients. So the researchers looked at the factors that could influence the effectiveness of the flu vaccine in older patients.

For the study, the team tracked the mood, diet, exercise and sleep patterns three times a day for 138 older adults (ages 65 to 85) over a period of six weeks prior to getting their flu shots. After the participants were vaccinated, researchers measured the amount of influenza antibodies they produced at four and 16 weeks from the date of injection.

Researchers did not find any link between any of the factors affecting one's physical and psychological health and the effectiveness of the flu shot except for one — positive mood. Overall, participants who reported being in a good mood over the six week period prior to vaccination had higher levels of antibodies in their blood after vaccination. The effect was even more pronounced for those who reported being in a good mood on the day of injection — that factor boosted antibody levels by as much as 8 to 14 percent.

Study results were published in the journal “Brain, Behaviour and Immunity”.