Covid 19: Exercise can amplify the benefits of a COVID-19 or flu vaccine

According to a new study on exercise and vaccination, taking a long brisk walk, jog or bike ride after your next COVID-19 or flu shot could amplify the benefits of the vaccine. The study, which involved 70 people and about 80 mice, looked at antibody responses after either a flu vaccine or both cycles of the Pfizer-BioNTech COVID-19 vaccine.

He found that people who exercised for 90 minutes right after their injection subsequently produced more antibodies than people who didn’t. The extra immune boost, which should help reduce their risk of getting seriously ill from these illnesses, doesn’t seem to trigger an increase in side effects.

The results of the study are preliminary and need to be tested on a larger number of people. But the findings add to growing evidence that being fit and physically active can prompt our bodies to respond with extra robustness to flu and COVID-19 vaccines.

Exercise changes “almost all” our immune cells
The relationship between exercise and immunity is, in general, well established. Most studies show that physical activity helps protect us against colds and other mild upper respiratory infections. Being fit can also lessen the severity of an infection if we get sick. In a study last year of nearly 50,000 Californians who developed COVID-19, for example, those who exercised regularly before their diagnosis were about half as likely to end up hospitalized as people who died. rarely trained.

On the other hand, extreme exercise could undermine our immunity. Marathon runners often report getting sick after races, and lab mice that run to exhaustion tend to become more susceptible to influenza than sedentary animals.

Overall, however, exercise seems to provide a powerful boost to our immune system. “The behavior of nearly all immune cell populations in the bloodstream is altered in some way during and after exercise,” concluded a recent review of previous research on the topic.

It is therefore not surprising that exercise can also affect the vaccine response. In some previous studies, performing arm exercises before a flu shot increased levels of antibodies and specialized immune cells afterward more than just sitting quietly. And in a 2020 study, elite competitive athletes in the middle of their training seasons generated more antibodies and immune cells after a flu shot than a control group of healthy young people.

Is there a good “dose” of exercise?

But few of these previous studies aimed to determine the best time and amount of exercise to amplify vaccine effects, and none examined COVID-19 injections, which have only been available since late 2020. Thus, for the new study, published recently in Brain, Behavior, and Immunity, a group of immunobiologists and exercise scientists at Iowa State University in Ames asked people who were getting their flu or COVID shots -19 to train as well.

They started by inviting dozens of healthy adults between the ages of 18 and 87 who said they exercised occasionally to come to the lab for flu shots. Scientists also coordinated with local COVID-19 vaccination sites to recruit 28 men and women who were receiving their first COVID-19 vaccines. Before the vaccinations, they took blood from all the volunteers to check the antibody levels.

Then they randomly assigned everyone to either sit quietly or exercise for 90 minutes after getting their shot. Previous research had suggested that exercising after receiving a vaccine increased the immune response more than the same level of activity before. And they chose 90 minutes as their general exercise goal because unpublished research from their lab suggested that the amount of exercise dramatically increases the production of a substance in the blood called interferon alfa that can trigger the creation of cells. immune.

The exercising volunteers then rode stationary bikes or briskly walked for 90 minutes after their vaccinations, either in the lab or outdoors on sidewalks near COVID-19 vaccination sites. They trained at a slightly challenging pace, aiming to keep their heart rate between around 120 and 140 beats per minute. But the researchers also asked some of the flu-vaccinated volunteers to ride for just 45 minutes, to see if the shorter workout might be just as effective in boosting immunity.

Since antibody levels tend to build up in the weeks following a vaccination, the researchers again drew blood from everyone two and four weeks after their injections. (People receiving the COVID-19 vaccine received their second injection in the meantime, as a second Pfizer injection should be given three weeks after the first.)

45 minutes is not enough
After a month, everyone’s antibody levels against the flu or the COVID-19 vaccine increased dramatically, as expected after receiving a vaccine. But they were highest in men and women who exercised for 90 minutes afterward. This antibody bonus was not huge. “But it was statistically significant,” said Marian Kohut, professor of kinesiology and fellow at Iowa State’s Nanovaccine Institute, who supervised the new study.

People who exercised also did not report any additional side effects after their injections. (They also didn’t experience fewer side effects.)

Interestingly, 45 minutes of exercise in this study was not enough to increase antibodies. The shorter workout likely didn’t increase levels of substances needed to boost immunity, including interferon alfa, Kohut said.

The researchers also repeated the flu vaccine experiment in mice that then jogged or stood still. The researchers checked their blood for interferon alfa levels and found them to be higher with exercise. But if the scientists chemically blocked the production of the substance, the animals gained some extra antibodies through exercise, suggesting that exercise partly improves vaccine response by first increasing interferon levels. alpha.

The upshot of the findings, then, is that “if you have the time and a safe place to exercise after your vaccination,” a 90-minute moderate exercise session may increase your vaccine response, Kohut said, without adding additional details. ‘Side effects.

Is 60 minutes enough?

The study was small, however, and did not measure antibody levels for more than a month after vaccination. It also didn’t track whether people eventually became infected with the flu or COVID-19, or look at levels of various other cells that could affect the immune response, Kohut pointed out.

An hour and a half is also a lot of exercise. “It’s important to remember that quite a sustained effort was required, 90 minutes at an increased heart rate,” said Carmine Pariante, a professor at King’s College London and editor of the journal in which the study is published. appeared. “The combination of three different vaccines in humans and in an animal model is a unique strength of this study,” Pariante said, adding that it was reassuring that the heightened antibody responses were present regardless of fitness level. physique of the vaccine recipient.

Researchers hope to study whether 60 minutes or other durations or intensities of exercise might be helpful — or vice versa — after vaccinations, and how long antibody responses might persist. They are already recruiting people for a longer-term study of the effects of exercise on COVID-19 booster shots.

But for now, if you’re planning a flu or COVID-19 shot, you can block out an extra 90 minutes to quickly explore the nearby neighborhood on foot or by bike. It may just provide an extra immune boost from your vaccine.

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Richard V. Johnson