Exercise after taking Covid and flu vaccine can boost effect

Taking a long, brisk walk, jog, or bike ride after your next Covid or influenza shot can intensify the vaccine’s benefits, a new study on exercise and immunization has revealed.

Done with 70 people and 80 mice, the study looked at antibody responses after an injection of the influenza vaccine or two doses of Pfizer-BioNTech’s Covid vaccine.

People who exercised for 90 minutes immediately after receiving the injection were found to produce more antibodies than others. The additional immune booster, which should help reduce the risk of becoming seriously ill with Covid or influenza, does not appear to have had any worsening side effects.

The study results are preliminary and still need to be tested with a larger number of people. But it adds to mounting evidence that being fit and physically active can prepare the body to respond especially well to influenza and Covid vaccines.

PHYSICAL EXERCISE CHANGES ‘ALMOST ALL’ IMMUNE CELLS

The relationship between exercise and immunity is already widely known. Most studies show that being physically active helps protect us against colds and other mild upper respiratory infections.

Being in good physical shape can also help reduce the severity of an infection if you get it. For example, a study last year of nearly 50,000 Californians who developed Covid found that those who exercised regularly before diagnosis were half as likely to end up hospitalized, compared to people who rarely exercised.

Extreme exercise can weaken our immunity. Marathoners often report getting sick after running, and lab rats that run to exhaustion tend to be more susceptible to influenza compared with sedentary animals.

Overall, though, exercise seems to give our immune system a powerful boost. “The behavior of nearly all immune cell populations in the blood is modified in some way during and after exercise,” concluded a recent review of past research on the topic.

So it should come as no surprise that exercise can also affect vaccine response. Some past studies have shown that doing arm exercises before getting a flu shot raised the number of antibodies and specialized immune cells afterwards, more so than just sitting still without moving.

And in a 2020 study, competitive elite athletes midway through their training seasons generated more antibodies and immune cells after getting a flu shot than was the case with a control group made up of healthy youth.

IS THERE A ‘CORRECT’ DOSE OF EXERCISE?

But few of these previous studies have sought to identify the best timing and duration of exercise to amplify the effects of vaccines, and none have looked at Covid vaccines, which have only been available since late 2020.

So for the new study, published this week in the journal Brain, Behavior, and Immunity, a group of immunobiologists and exercise scientists at Iowa State University in Ames, Iowa, asked people who were going to receive an influenza or Covid vaccine to exercise.

They began by inviting dozens of healthy adults ages 18 to 87 who said they exercise occasionally to come to the lab to get a shot of the influenza vaccine.

And the scientists combined with local Covid vaccination points to recruit 28 men and women who were going to receive the first dose of Covid vaccine. Before the vaccines, they took blood from all the volunteers to check their antibody levels.

After that, they randomly instructed people to either sit quietly or exercise for 90 minutes after receiving the injection. Previous research had suggested that exercising after receiving a vaccine boosts the immune response more than the same level of exercise before the vaccine.

They set 90 minutes as an overall exercise goal because unpublished research from their lab suggested that this amount of exercise strongly increases the production of a substance in the blood called interferon alpha that can trigger the creation of immune cells.

So the exercise volunteers rode a stationary bike or walked briskly for 90 minutes after receiving the vaccine, either in the lab or on the sidewalks near Covid vaccination sites.

They worked out at a slightly tiring pace, aiming to keep their heart rate between 120 and 140 beats per minute.

But the researchers also asked some of the influenza-vaccinated volunteers to exercise for just 45 minutes, to see if the shorter time would have the same immunity-boosting effect.

As antibody levels tend to rise in the weeks following vaccination, the scientists took blood from all volunteers two weeks and then four weeks after vaccination. (People who received the Covid vaccine received the second dose during this time, as the second dose of Pfizer’s vaccine must be given three weeks after the first.)

45 MINUTES IS NOT ENOUGH

After a month, the levels of antibodies against influenza or Covid in all participants had risen sharply, as expected after inoculation. But they were higher in men and women who had exercised for 90 minutes after vaccination.

The margin of difference in antibodies was not huge. “But it was statistically significant,” said Marian Kohut, a professor of kinesiology and a member of the Nanovaccine Institute at Iowa State University, who oversaw the new study.

People who exercised did not report additional side effects after the vaccine (nor did they have fewer side effects).

An interesting fact was that, according to the study, 45 minutes of exercise was not enough to raise the level of antibodies. According to Kohut, the shorter time of exercise probably did not raise the levels of substances needed to boost immunity.

The researchers repeated the experiment with the influenza vaccine with mice that either ran or stood still after the vaccine. They examined the mice’s blood for interferon alpha levels and saw that they rose with exercise.

But if the scientists chemically blocked the production of the substance, the animals’ antibodies rose little with exercise, a fact that suggests that exercise improves the response to vaccines in part because it first raises levels of alpha interferon.

The bottom line, Kohut said, is therefore that “if you have the time and a safe place to exercise after you get the vaccine,” a 90-minute bout of moderate physical exercise can amplify your response to the vaccine, without increasing side effects. her.

CAN 60 MINUTES BE ENOUGH?

But the study was small and did not measure antibody levels for more than a month after vaccination. Nor did it follow the participants to see if they later contracted influenza or Covid, nor did it analyze the levels of various other cells that can affect the immune response, Kohut pointed out.

An hour and a half is a lot of exercise. “It’s important to remember that it took sustained effort: 90 minutes at an elevated heart rate,” said Carmine Pariante, a professor at King’s College London who is editor of the journal in which the study appeared.

“The combination of three different vaccines in humans and in an animal model is a unique strength of this study,” he commented, adding that it is reassuring to know that the increased antibody responses occurred regardless of the fitness level of the vaccinated persons.

The researchers hope to study whether 60 minutes or other exercise durations or intensities can help — or the opposite — after vaccination and how long antibody responses can last. They are already recruiting people for a longer-term study of the effects of physical exercise on booster doses of the anti-Covid vaccine.

For now, though, if you’re going to get a flu shot or Covid shot, it’s worth setting aside 90 minutes to get around the surrounding area on foot or by bike, walking briskly, right after being vaccinated. As a result, the vaccine you have had may give you additional immune protection.

_{Translation by Clara Allain}