Exercise immunology: Part 1 | Part 2
Can you run after a vaccine? What the evidence says
Thomas Solomon, PhD.
This page contains an evidence-based look at whether you should train after a vaccine, with a focus on runners and endurance athletes and the immune response that vaccines are designed to trigger.
The content is for endurance athletes who’ve been told “no sport for 2–3 days” after vaccination and want clear, science-led guidance on what to do with training.
Key takeaway: The vaccine injection site commonly causes local inflammation—soreness, redness, swelling, heat, and reduced function—so arm-loaded training (heavy lifting, rowing, ski-erg, climbing) can be painful and may worsen swelling until it settles.
Key takeaway: Two studies designed specifically around exercise after vaccination found no meaningful benefit or harm for antibody responses, and a newer 2022 trial reported larger antibody responses after 90 minutes of light-to-moderate exercise compared with no exercise. But, the evidence on post-vaccine exercise is limited.
Key takeaway: If you feel unwell after a vaccine, don’t train—rest and recover. Otherwise, keep moving, but basically ease off for a couple of days and don’t go ruin yourself with a race or a string of hard sessions while the body is using energy and nutrients to build the immune response.
But, don’t stop there! Scroll down to fully educate yourself on the details, nuances, and nerdy bits.
Have you ever been told not to 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, and what I found was quite interesting, so I thought I’d share it…
Let’s dive in…
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, the docs did not recommend that I avoid other unhealthy behaviours, such as alcohol or smoking, which is amusing because I was essentially being recommended to avoid a healthy behaviour: exercise.
Two weeks before writing this post, 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.
What happens after a vaccine and why you’re told “no sport”.
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 change vaccine response? Immunogenicity explained.
In other words, does exercise improve or impair how well the vaccine endows us with the acquired immunity we need to be protected against future exposure to the disease?
Of course, we 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.
What is the evidence on vaccine efficacy after exercise?
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 little 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 compiling 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 clear information to help clinicians inform athletes what to do with their training after they’ve received a vaccine.
In the meantime, to keep it simple:
What should athletes do after a vaccine?
If you develop disease symptoms and/or feel shit, don’t train. Rest, recover, and come back stronger (NOTE: that advice is not only relevant 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, or a series of hard sessions. Keep moving but step off the gas for a couple of days; go easy and prioritise health.
Until next time, stay nerdy and keep empowering yourself to be the best athlete you can be by training smart.
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Who is Thomas Solomon?
My knowledge has been honed following 20+ years of running, cycling, hiking, cross-country skiing, lifting, and climbing, 15+ years of academic research at world-leading universities and hospitals, and 10+ years advising and coaching in athletic performance and lifestyle change.
I have a BSc in Biochemistry, a PhD in Exercise Science, and over 90 peer-reviewed publications in medical journals.
I'm also an ACSM-certified Exercise Physiologist (ACSM-EP), an ACSM-certified Personal Trainer (ACSM-CPT), a VDOT-certified Distance Running Coach, and a UKVRN Registered Nutritionist (RNutr).
Since 2002, I’ve conducted biomedical research in exercise and nutrition and have taught and led university courses in exercise physiology, nutrition, biochemistry, and molecular medicine.
And, with my personal experience of competing on the track (800m to 10,000m), the road (5 k to marathon), on the trails, and in the mountains, by foot, bicycle, cross-country ski, and during obstacle course races (OCR), I deeply understand what it's like to train and compete — I've been there, done it, and gotten sweat, mud, and tears on my t-shirt.
Disclaimer: I occasionally mention brands and products, but it is important to know that I don't sell recovery products, supplements, or ad space, and I'm not affiliated with / sponsored by / an ambassador for / receiving advertisement royalties from any brands. I have conducted biomedical research for which I’ve received research money from publicly-funded national research councils and medical charities, and also from private companies, including Novo Nordisk Foundation, AstraZeneca, Amylin, the A.P. Møller Foundation, and the Augustinus Foundation. I’ve also consulted for Boost Treadmills and Gu Energy on R&D grant applications, and I provide research and scientific writing services for Examine.com. Some of my articles contain links to information provided by Examine.com, but I do not receive any royalties or bonuses from those links. Importantly, none of the companies described above have had any control over the research design, data analysis, or publication outcomes of my work. I research and write my content using state-of-the-art, consensus, peer-reviewed, and published scientific evidence, combined with my empirical evidence observed in practice and feedback from athletes. My advice is, and always will be, based on my own views and opinions shaped by the scientific evidence available. The information I provide is not medical advice. Before making any changes to your habits of daily living based on any information I provide, always ensure it is safe for you to do so and consult your doctor if you are unsure.
