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Exercise immunology:
“No sport today”... Should you train after a vaccine?

Thomas Solomon PhD.
28th May 2022.
Have you ever been told not to do exercise after a vaccine? I have. Four times in the last 9-months. So, I dug into the “don’t do any exercise” advice to see what’s up… What I found was quite interesting, so I thought I’d share it…

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When going for my COVID vaccines over the past year or so, I’ve received the same advice on all three visits:
“No sport for 2 to 3 days after your vaccine.”
At the first appointment, I asked the doctor why. The response: “Because it alters the effectiveness of the vaccine”.
I found the word “alters” somewhat ambiguous because it doesn’t specify in which way the vaccine’s effectiveness is affected — does it impair or improve the effectiveness? At that time, I also suspected there couldn't possibly be data exploring the effect of exercise on the immunogenicity of this particular vaccine because the COVID-19 vaccine had only been approved a few weeks prior. Furthermore, there was no mention of avoiding other unhealthy behaviours, such as alcohol or smoking — I found this amusing because I was, in essence, being recommended to avoid a healthy behaviour: exercise.
Two weeks ago, I had a vaccine against tick-borne encephalitis (TBE) as well as my Repevax booster against diphtheria, tetanus, pertussis, and polio. When being bandaged up after the injections, I received similar advice:
“No sport after the vaccines today.”
(once again with no advice regarding other unhealthy behaviours).
Now, my spidey senses were tingling — I was intrigued.
From a pragmatic perspective, an intramuscular injection causes a microscopic “wound” in your skin and muscle fascia and places a small volume of fluid containing a “foreign body” (the antigen that will trigger your immunity to a specific disease) into your muscle (most often the deltoid muscle on your upper arm). This process causes an expected immune response, which includes local inflammation at the injection site — soreness, redness, swelling, heat, and a loss of function.
Local inflammation is a normal response to an injection but the consequence is that it can be difficult to use said muscle for normal tasks. This means that exercise involving your arms might be difficult, even painful. Plus, arm exercise will likely cause more swelling in the muscle, thus delaying the recovery of the inflammatory processes. For this reason, it is wise to avoid heavy lifting, rowing, ski-erging, climbing, and anything else that places a load on your arms until the swelling subsides. Alas, most runners probably don’t do any such things, so no worries there.
But the important question is whether exercise directly affects the immunogenicity of a vaccine. Epic jargon that is more easily understood by asking…
Does exercise “alter” (impair or improve) how well the vaccine endows us with the acquired immunity required to confer protection against future exposure to the disease?
Of course, you can always find case studies of unusual and rare outcomes. For example, I found a case report of neuropathy (nerve dysfunction) developing after vaccination against tick-borne encephalitis and tetanus (6-days apart) in one 45-year-old female athlete. But case reports simply show what rare events are possible, not what is highly probable or causal. For that, we need randomised controlled trials.
One major limitation in trying to answer the question, “Does exercise alter vaccine effectiveness?” is that it’s almost impossible to determine whether the relative risk reduction of disease is changed by exercise. Of course, we cannot run a randomised controlled trial in which we’d purposefully provide subjects with an infectious disease. Instead, it would require a massive trial of folks randomised to a post-vaccine exercise intervention or a post-vaccine no-exercise control group, with a follow-up to determine how many folks in each group get the disease of interest over the coming months. This approach would only really work with highly prevalent diseases that folks are regularly exposed to (e.g. flu, SARS-CoV-19, etc). But this study is far too epic to ever happen.
So we need an alternative approach to answer the question…
And that approach is what the vast majority of studies in the exercise-vaccine world do — they measure changes in post-vaccine antibody titres, not actual disease incidence. This approach is useful because it tells us whether the vaccine has triggered an immune response to produce the relevant antibody needed to help a person fight an infection if they’re exposed to the disease.
A 2020 systematic reviewA systematic review answers a specific research question by systematically collating all known experimental evidence, which is collected according to pre-specified eligibility criteria. A systematic review helps inform decisions, guidelines, and policy. by Vedhara and colleagues, which investigated the effects of all non-pharmacological interventions as vaccine adjuvants, identified only 11 exercise-related randomised controlled trials: 7 involving influenza (“flu”) vaccines, 2 including pneumococcal vaccines, and one study examining the meningococcal A & C vaccine. The authors concluded that “Two-thirds of all trials (k = 8/12) and RCTs (k = 7/9) reported some evidence of an enhanced antibody response to vaccination in the intervention arm.”. (Note that “all trials” means both non-randomised and randomised and “intervention arm” means the exercise groups.)
But this is a rather vague and subjective analysis.
Despite conducting a network meta-analysis of all data (essentially pooling all non-pharmacological interventions including exercise, nutrition, psychology, etc), the authors did not meta-analyseA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all studies of that treatment. the exercise data. This is partly because, within the 11 exercise-related trials, there is a variable array of study designs including training interventions or single exercise bouts, and during-exercise vaccinations or pre- or post-vaccination exercise. In fact, only 2 studies were designed with an exercise intervention after the administration of a vaccine, which is the type of study we need to understand the “no sport after your vaccine” advice.
What did those 2 studies show?
Nothing of note. Post-vaccine exercise had neither a beneficial nor a detrimental effect on vaccine immunogenicity. But a new 2022 study, hot-off-the-press from Hallam et al. reported that subjects who completed 90-mins of light to moderate intensity exercise after receiving an influenza vaccine (N=20) or the Pfizer/BioNTech mRNA COVID vaccine (N=36) had larger antibody responses in the weeks following vaccination compared to folks who did not exercise.
So, at present, the data is sparse and we are far from being able to produce a robust meta-analysisA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all studies of that treatment. of post-vaccine exercise effects. But, the data certainly isn’t swaying in support of “no sport after your vaccine” advice.
Speaking of meta-analyses, a 2016 Cochrane review by Grande et al. examined the effect of pre- (not post-) vaccine exercise on influenza vaccination. They concluded:
This conclusion is echoed in the findings of another hot-off-the-press randomised controlled trial examining the effects of prior exercise on the immunogenicity of vaccines against SARS-CoV-2 (in immunocompromised folks). So, although this is not relevant to our post-vaccine exercise question, again it shows that exercise is not an evildoer in your quest for immunogenicity.
As you can see, there’s a lot of methodological variability in the exercise-vaccine world and not a lot is known about the effects of post-vaccine exercise. Plus, what is known certainly doesn’t show a detrimental effect of exercise on vaccine effectiveness. Therefore, it is difficult to justify a blanket statement of “No sport after your vaccine” because there is insufficient data to draw from. This doesn’t mean it’s bad advice but, in my opinion, the nuance of science is being lost in translation for an athlete seeking a vaccine amidst a training block.
Consequently, there is little clarity in this field. We don’t know the true effect of post-vaccine exercise on vaccine immunogenicity. And, there are many unanswered questions, namely:
Does exercise differentially affect the immunogenicity of vaccines for different diseases? E.g. influenza vs. pneumococcal vs. meningococcal vs. COVID vaccines, etc.
And
Does exercise differentially affect the immunogenicity of different types of vaccine? E.g. inactivated virus vaccines (influenza) vs. live attenuated virus vaccines (chickenpox, MMR) vs. mRNA vaccines (Pfizer/BioNTech COVID), etc.
Because of the unknowns, it is no surprise that public health officials including medical doctors are unaware of the reasons for their “no sport today” advice. So, I guess this post becomes a nudge to exercise immunology researchers — please conduct high-quality randomised controlled trialsThe “gold standard” approach for determining whether a treatment has a causal effect on an outcome of interest. In such a study, a sample of people representing the population of interest is randomised to receive the treatment or a no-treatment placebo (control), and the outcome of interest is measured before and after the exposure to treatment/control. examining the effects of post-vaccine exercise and compile those trials in a systematic reviewA systematic review answers a specific research question by systematically collating all known experimental evidence, which is collected according to pre-specified eligibility criteria. A systematic review helps inform decisions, guidelines, and policy. with meta-analysisA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all studies of that treatment. to inform public health policy. Only then will there be crystal clear information to help clinicians inform athletes what to do with their training when they’ve received a vaccine.
In the meantime, to keep it simple:

I found the word “alters” somewhat ambiguous because it doesn’t specify in which way the vaccine’s effectiveness is affected — does it impair or improve the effectiveness? At that time, I also suspected there couldn't possibly be data exploring the effect of exercise on the immunogenicity of this particular vaccine because the COVID-19 vaccine had only been approved a few weeks prior. Furthermore, there was no mention of avoiding other unhealthy behaviours, such as alcohol or smoking — I found this amusing because I was, in essence, being recommended to avoid a healthy behaviour: exercise.
Two weeks ago, I had a vaccine against tick-borne encephalitis (TBE) as well as my Repevax booster against diphtheria, tetanus, pertussis, and polio. When being bandaged up after the injections, I received similar advice:

(once again with no advice regarding other unhealthy behaviours).
From a pragmatic perspective, an intramuscular injection causes a microscopic “wound” in your skin and muscle fascia and places a small volume of fluid containing a “foreign body” (the antigen that will trigger your immunity to a specific disease) into your muscle (most often the deltoid muscle on your upper arm). This process causes an expected immune response, which includes local inflammation at the injection site — soreness, redness, swelling, heat, and a loss of function.
Local inflammation is a normal response to an injection but the consequence is that it can be difficult to use said muscle for normal tasks. This means that exercise involving your arms might be difficult, even painful. Plus, arm exercise will likely cause more swelling in the muscle, thus delaying the recovery of the inflammatory processes. For this reason, it is wise to avoid heavy lifting, rowing, ski-erging, climbing, and anything else that places a load on your arms until the swelling subsides. Alas, most runners probably don’t do any such things, so no worries there.
But the important question is whether exercise directly affects the immunogenicity of a vaccine. Epic jargon that is more easily understood by asking…

One major limitation in trying to answer the question, “Does exercise alter vaccine effectiveness?” is that it’s almost impossible to determine whether the relative risk reduction of disease is changed by exercise. Of course, we cannot run a randomised controlled trial in which we’d purposefully provide subjects with an infectious disease. Instead, it would require a massive trial of folks randomised to a post-vaccine exercise intervention or a post-vaccine no-exercise control group, with a follow-up to determine how many folks in each group get the disease of interest over the coming months. This approach would only really work with highly prevalent diseases that folks are regularly exposed to (e.g. flu, SARS-CoV-19, etc). But this study is far too epic to ever happen.
So we need an alternative approach to answer the question…
And that approach is what the vast majority of studies in the exercise-vaccine world do — they measure changes in post-vaccine antibody titres, not actual disease incidence. This approach is useful because it tells us whether the vaccine has triggered an immune response to produce the relevant antibody needed to help a person fight an infection if they’re exposed to the disease.
A 2020 systematic reviewA systematic review answers a specific research question by systematically collating all known experimental evidence, which is collected according to pre-specified eligibility criteria. A systematic review helps inform decisions, guidelines, and policy. by Vedhara and colleagues, which investigated the effects of all non-pharmacological interventions as vaccine adjuvants, identified only 11 exercise-related randomised controlled trials: 7 involving influenza (“flu”) vaccines, 2 including pneumococcal vaccines, and one study examining the meningococcal A & C vaccine. The authors concluded that “Two-thirds of all trials (k = 8/12) and RCTs (k = 7/9) reported some evidence of an enhanced antibody response to vaccination in the intervention arm.”. (Note that “all trials” means both non-randomised and randomised and “intervention arm” means the exercise groups.)
But this is a rather vague and subjective analysis.
Despite conducting a network meta-analysis of all data (essentially pooling all non-pharmacological interventions including exercise, nutrition, psychology, etc), the authors did not meta-analyseA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all studies of that treatment. the exercise data. This is partly because, within the 11 exercise-related trials, there is a variable array of study designs including training interventions or single exercise bouts, and during-exercise vaccinations or pre- or post-vaccination exercise. In fact, only 2 studies were designed with an exercise intervention after the administration of a vaccine, which is the type of study we need to understand the “no sport after your vaccine” advice.
What did those 2 studies show?
Nothing of note. Post-vaccine exercise had neither a beneficial nor a detrimental effect on vaccine immunogenicity. But a new 2022 study, hot-off-the-press from Hallam et al. reported that subjects who completed 90-mins of light to moderate intensity exercise after receiving an influenza vaccine (N=20) or the Pfizer/BioNTech mRNA COVID vaccine (N=36) had larger antibody responses in the weeks following vaccination compared to folks who did not exercise.
So, at present, the data is sparse and we are far from being able to produce a robust meta-analysisA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all studies of that treatment. of post-vaccine exercise effects. But, the data certainly isn’t swaying in support of “no sport after your vaccine” advice.
Speaking of meta-analyses, a 2016 Cochrane review by Grande et al. examined the effect of pre- (not post-) vaccine exercise on influenza vaccination. They concluded:
This conclusion is echoed in the findings of another hot-off-the-press randomised controlled trial examining the effects of prior exercise on the immunogenicity of vaccines against SARS-CoV-2 (in immunocompromised folks). So, although this is not relevant to our post-vaccine exercise question, again it shows that exercise is not an evildoer in your quest for immunogenicity.
As you can see, there’s a lot of methodological variability in the exercise-vaccine world and not a lot is known about the effects of post-vaccine exercise. Plus, what is known certainly doesn’t show a detrimental effect of exercise on vaccine effectiveness. Therefore, it is difficult to justify a blanket statement of “No sport after your vaccine” because there is insufficient data to draw from. This doesn’t mean it’s bad advice but, in my opinion, the nuance of science is being lost in translation for an athlete seeking a vaccine amidst a training block.
Consequently, there is little clarity in this field. We don’t know the true effect of post-vaccine exercise on vaccine immunogenicity. And, there are many unanswered questions, namely:

And

In the meantime, to keep it simple:
After your vaccine,
If you develop disease symptoms and/or feel shit, don’t train. Rest, recover, and come back stronger (advice that is not only specific to having had a vaccine).
Avoid heavy lifting and arm-specific exercises until the soreness & swelling have subsided to allow the injection site “wound” and muscle damage to heal.
And,
To produce antibodies that could save your life, the vaccine needs to use your bodily resources (nutrients & energy). Don’t jeopardise that by depleting all your resources by ruining yourself with a race, an epic session, a or series of hard sessions. Keep moving but step off the gas for a couple of days; go easy and prioritise health.
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About the author:
I am Thomas Solomon and I'm passionate about relaying accurate and clear scientific information to the masses to help folks meet their fitness and performance goals. I hold a BSc in Biochemistry and a PhD in Exercise Science, and am an ACSM-certified Exercise Physiologist and Personal Trainer, a VDOT-certified Distance running coach, and a Registered Nutritionist. Since 2002, I have conducted biomedical research in exercise and nutrition and have taught and led university courses in exercise physiology, nutrition, biochemistry, and molecular medicine. My work has been published in over 80 peer-reviewed medical journals publications and I have delivered more than 50 conference presentations & invited talks at universities and medical societies. I have coached and provided training plans for truck-loads of athletes, have competed at a high level in running, cycling, and obstacle course racing, and continue to run, ride, ski, hike, lift, and climb as much as my ageing body will allow. To stay on top of scientific developments, I consult for scientists, participate in journal clubs, peer-review papers for medical journals, and I invest every Friday in reading what new delights have spawned onto PubMed. In my spare time, I hunt for phenomenal mountain views to capture through the lens, boulder problems to solve, and new craft beers that send my gustatory system into a hullabaloo.
Copyright © Thomas Solomon. All rights reserved.
I am Thomas Solomon and I'm passionate about relaying accurate and clear scientific information to the masses to help folks meet their fitness and performance goals. I hold a BSc in Biochemistry and a PhD in Exercise Science, and am an ACSM-certified Exercise Physiologist and Personal Trainer, a VDOT-certified Distance running coach, and a Registered Nutritionist. Since 2002, I have conducted biomedical research in exercise and nutrition and have taught and led university courses in exercise physiology, nutrition, biochemistry, and molecular medicine. My work has been published in over 80 peer-reviewed medical journals publications and I have delivered more than 50 conference presentations & invited talks at universities and medical societies. I have coached and provided training plans for truck-loads of athletes, have competed at a high level in running, cycling, and obstacle course racing, and continue to run, ride, ski, hike, lift, and climb as much as my ageing body will allow. To stay on top of scientific developments, I consult for scientists, participate in journal clubs, peer-review papers for medical journals, and I invest every Friday in reading what new delights have spawned onto PubMed. In my spare time, I hunt for phenomenal mountain views to capture through the lens, boulder problems to solve, and new craft beers that send my gustatory system into a hullabaloo.
Copyright © Thomas Solomon. All rights reserved.