Does a Good Mood Affect How Well the Flu Vaccine Works?

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Could people’s mood impact how strongly their immune system responds to the influenza (flu) vaccine? It's a provocative idea, to be sure, but a new study, published online this month in Health Psychology, set out to answer that question with the help of a lighthearted video.

A shot in the arm for seniors?

To maximize the potential benefits, the researchers behind the study focused on older adults (ages 65-85). The Centers for Disease Control and Prevention (CDC) stresses that getting the flu vaccine every year is the best line of defense against flu. Yet there’s room for improvement in how effective the vaccine is for this age group.

“We know that the flu vaccine does not work as well in older people as it does in younger people,” says study coauthor Kavita Vedhara, Ph.D., a professor of health psychology at the University of Nottingham in England. “One of the main reasons is because the effectiveness of the immune system declines with advancing age.”

This gradual deterioration is known as immune senescence. It not only decreases vaccine effectiveness but also increases susceptibility to infectious illnesses and their serious complications. In the U.S., the CDC estimates that 50% to 70% of flu-related hospitalizations occur in people ages 65 and older.

In a good mood on flu shot day

To understand the latest research, it helps to know what led up to it. In 2018, the University of Nottingham research team published a related study in Brain, Behavior, and Immunity. That study included 138 older adults who were living independently in the community.

For two weeks before and four weeks after getting their annual flu shot, the participants in this study repeatedly answered questions about their mood, diet, sleep, and stress level. They also wore pedometers at certain times to estimate their physical activity.

Vaccines work by stimulating the immune system to produce antibodies, which confer protection against the target disease. To measure the participants’ short-term and long-term antibody responses to the flu vaccine, the researchers took blood samples.

The result: The study showed that a positive mood, especially on the day of vaccination, was associated with a stronger response to a particular strain of the flu vaccine.

What other researchers have found

More research is needed to confirm this finding. But numerous other studies have also found a link between psychological well-being and the immune system’s response to vaccination.

For example, a 2012 study from the University of Kentucky showed that the combination of a low body mass index (BMI, a measure of body fatness) and low psychological distress was associated with a more robust antibody response to the flu vaccine in older adults. Likewise, the combo of increased physical activity and decreased distress was also linked to a stronger response.

Research has been conducted in healthy, younger people as well. Consider a 2018 study authored by Brooke Jenkins, Ph.D., an assistant professor of psychology at Chapman University in Orange, California. Among other things, Jenkins and her colleagues looked at positive affect (feelings such as happiness, cheerfulness, and being relaxed) and affect variability (how much someone’s affect goes up and down).

“We found that people with generally high positive affect that fluctuated quite a bit had a lower antibody response to the flu vaccination,” Jenkins says. “In contrast, people with generally high positive affect that fluctuated less had a higher antibody response. In other words, a good flu vaccine response was more common in people who had consistently high levels of positive affect.”

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Keep in mind that the average age of participants in Jenkins’ sample was 18. In young, healthy people, even those with a “lower” antibody response may still respond pretty well. “In our sample, nearly all our participants had antibody responses that were above the cutoff for being clinically protective,” Jenkins says.

What the just-published study showed (and did not show)

In older adults, there’s more opportunity to reduce flu-related complications and deaths due to immune senescence. But how could the link between positive feelings and vaccine response be harnessed for this purpose?

To begin answering this question, the University of Nottingham team created a 15-minute video designed to make people smile. “It consisted primarily of music and comedy selected for its appeal to older people in the U.K.,” says Vedhara. Translation: There was plenty of Elvis and Fawlty Towers.

The researchers then enlisted 109 older adults, who were randomly assigned to watch either the upbeat video or an emotionally neutral video just prior to getting a flu shot. Their mood was assessed before and after the video, and their antibody response to the vaccine was measured one and four months later.

“Our primary aim in this study was to see if it was possible to briefly improve positive mood in older people at the time they were being vaccinated,” Vedhara says. And indeed, it turned out that viewing the video put people in a more positive frame of mind.

The study’s secondary aim was to see if this mood boost affected antibody levels after vaccination. “While not statistically significant, we found evidence that antibody levels in people who received our intervention appeared to be enhanced,” says Vedhara.

In short, this small study did not establish that the video intervention improved vaccine responsiveness in older adults. But a larger study is needed for more definitive results.

Could YouTube give flu shots a boost?

Vedhara and her colleagues plan to keep exploring this line of research. Watching smile-worthy video clips costs next to nothing, takes little time, and is risk-free. So, even if any benefits of a peppy pre-vaccine video turn out to be modest, they could still be worth pursuing.

Chances are when you go to get the flu vaccine, you spend a few minutes waiting at the pharmacy or in your doctor’s office. Especially if you’re over age 65 or have a weakened immune system, should you spend that time watching fun video clips? “It can’t hurt!” Vedhara says.