Being in a positive mood on the day that you receive your flu jab can increase its protective effect, according to a study by the University of Nottingham.
Researchers noted that influenza vaccination was estimated to only be effective in 17-53% of older adults compared to 70-90% of younger people.
“Greater positive mood in older adults is associated with enhanced responses to vaccination”
They said that, with the onset of winter, their findings were likely to be of interest to those taking part in the annual flu vaccination programme.
The study is the first to examine several psychological and behavioural factors that have been shown to affect how well vaccinations work.
The East Midlands researchers set out to understand which factor, or combination of factors, had the greatest impact on the ability of vaccinations to protect against disease.
The team measured negative mood, positive mood, physical activity, diet and sleep three times a week over a six-week period in a group of 138 older people due to have their flu jab in 2014-15.
They then examined how well the vaccine was working by measuring the amount of influenza antibody in the blood at four weeks and 16 weeks after immunisation.
“We have known for many years that psychological and behavioural factors influence how well the immune system work”
Among the factors measured, only positive mood over the six-week period predicted how well the jab worked, with good mood associated with higher levels of antibody, said the study authors.
In fact, when they looked at influences on the day of vaccination itself, mood was found to have an even greater impact – accounting for between 8% and 14% of the variability in antibody levels.
“No other factors were found to significantly predict antibody responses to vaccination,” said the researchers in the journal Brain, Behavior and Immunity.
“Greater positive mood in older adults, particularly on the day of vaccination, is associated with enhanced responses to vaccination,” they stated.
Senior study author Professor Kavita Vedhara, from the university’s primary care division, said: “Vaccinations are an incredibly effective way of reducing the likelihood of catching infectious diseases.
“But their Achilles heel is that their ability to protect against disease is affected by how well an individual’s immune system works,” she said. “So, people with less effective immune systems, such as the elderly, may find vaccines don’t work as well for them as they do in the young.
“We have known for many years that a number of psychological and behavioural factors such as stress, physical activity and diet influence how well the immune system works and these factors have also been shown to influence how well vaccines protect against disease,” she added.
The study was unusual, said the authors, because, by chance, the vaccination that participants received was identical to the one they had received in the previous year.
As a result, the researchers found patients had very high levels of antibody for two out of three of the viruses present in the vaccination, even before they were immunised.
This so-called “ceiling effect” meant the study was unlikely to see further large increases in antibody levels for these two viruses and, therefore, was unlikely to reveal an effect of psychological and behavioural factors.
As a result, the team focused its analyses on the one strain that was the least “immunogenic” – defined as the strain with low levels of antibody prior to vaccination.
The researchers recommended that future research would be best conducted in the context of a vaccination with more novel viral strains to further confirm the positive mood effect.
The study was funded by National Institute for Health Research and the Medical Research Council.