Mechanisms Behind Vaccine Side-Effects: The Science That Causes That Sore Arm

After receiving a vaccination shot, it’s likely that we’ll feel some side-effects. These can range from merely a sore arm to swollen lymph nodes and even a fever. Which side-effects to expect depend on the exact vaccine, with each type and variant coming with its own list of common side-effects. Each person’s immune system will also react differently, which makes it hard to say exactly what one can expect after receiving the vaccination.

What we can do is look closer at the underlying mechanisms that cause these side-effects, to try and understand why they occur and how to best deal with them. Most relevant here for the initial response is the body’s innate immune system, with dendritic cells generally being among the first to come into contact with the vaccine and to present the antigen to the body’s adaptive immune system.

Key to the redness, swelling, and fever are substances produced by the body which include various cytokines as well as prostaglandin, producing the symptoms seen with inflammation and injury.

Tackling the Intruder

Rendering of dendritic cell
Artistic rendering of a human dendritic cell. (Source: NIH)

The first difference between vaccines is found in how the antigen is introduced into the body. Traditional vaccines use either weakened whole viruses, or parts of viruses, which are thus the antigen or contain the intended antigen as part of their structure. Viral vector-based and mRNA (lipid-vector) vaccines use a vector that transfers RNA into the body’s cells, where the cell’s ribosomes then assemble copies of the antigen. As a foreign protein, this is then presented on the surface of the cell as an antigen to lymphocytes.

If antibodies exist already against this specific antigen, the lymphocytes (B and T cells) of the body’s adaptive immune system will immediately act upon this antigen, and thus the (presumed) intruder (virus, bacteria or toxin) that is attached to the antigen. If no antibodies exist, the process is similar, but takes a bit longer for the immune response to ramp up.

Meanwhile, as the adaptive immune system ramps up, the dendritic and other cells of the innate immune system which possess pattern recognition receptors (PRRs) for pathogen-associated molecular patterns (PAMPs) like macrophages and mast cells also release a number of cytokines, including inflammatory cytokines which cause vasodilation. The resulting influx of blood causes the reddening of the skin (rubor) and increased heat (calor) .

As the blood vessels dilate, other mediators act to make the walls of these vessels more permeable, causing the amount of fluid outside of the blood vessels (intracellular space) to increase. This exudation of fluid causes swelling (tumor) which decreases the likelihood of pathogens coming into contact with body tissues, while giving macrophages and other leukocytes (white blood cells) free roam so that they can hunt down pathogens.

In addition to the vasodilation process, some of the released cytokins cause hyperalgesia (dolor), essentially an increased sensitivity to pain. All of these form part of the acute inflammation process and are responsible for the ‘sore arm’ often experienced after getting a vaccination.

Fever From a Vaccine

Thermoregulation diagram
Simplified diagram of human thermoregulation (Author: J. W. Dietrich)

Among the symptoms commonly experienced after getting certain types of vaccines, fever (along with a headache) is not nearly as common as a sore arm, but still frequently reported. If we look at the CDC study results for the Pfizer-BioNTech mRNA vaccine for COVID-19 where people self-reported their symptoms, we can see headaches as a frequently reported symptom, however due to the prevalence in the placebo group of this symptom a strong causal link appears to be absent.

A more clear connection between vaccines and fevers exist, as one of the substances released during the inflammation process is an eicosanoid called prostaglandin. This compound is involved in vasodilation, as well as the inhibiting of blood platelet aggregation (anti-clotting) and most importantly in this case strongly affecting the body’s thermoregulatory center in the hypothalamus.

Simply put, the inflammatory response from the body’s innate and adaptive immune system results in a positive input to the body’s thermoregulatory system. The result from this can differ from merely experiencing some thermal discomfort, to actual fever where one’s body temperature can exceed its normal levels by a significant amount.

None of this is anything to worry about so long as the fever does not exceed 40 °C (104 °F), which as the earlier linked CDC vaccine study results show is exceedingly rare. It is safe to use an NSAID like ibuprofen to help with any fever as well as pain symptoms that may occur after the vaccination. As there is no real pathogen present from the vaccine, the only important factor is that the adaptive immune system gets an opportunity to learn the new antigen, meaning that there is no immunological benefit from developing a fever, let alone pain around the injection site.

Heart Inflammation

Viral myocarditis
Microscope image of heart tissue that suffered viral myocarditis.

Myocarditis (inflammatory cardiomyopathy) is an inflammation of the heart muscle which is most often caused by a viral infection. In an average year well over a million people world-wide will develop myocarditis, with over 300,000 patients dying from this condition. The cause of myocarditis is generally the infiltration of the heart muscle by pro-inflammatory white blood cells as a response to an infection. In the case of the SARS-CoV-2 virus, this pathogen directly binds to the ACE2 receptors on the heart tissue’s surface, allowing it to infect these cells.

In the case of the SARS-CoV-2 vaccines, myocarditis is a known, if rare, side-effect. An article by Biykem et al. speculates that its cause is molecular mimicry between the spike protein of SARS-CoV-2 viruses and self-antigens, including α-myosin. This is a protein also known as MYH6, and which is expressed significantly in both the cardiac atria and the cardiac ventricles.

In case of a mistaken identity by the adaptive immune system, this could lead to the heart muscle being targeted by leukocytes. Whether or not this is the actual mechanism responsible, David K. Shay et al. report that compared to natural occurrence of myocarditis, its occurrence in cases linked to COVID-19 immunization is exceedingly rare. Even so, without understanding the exact mechanism involved, any linking of specific myocarditis cases to a SARS-CoV-2 vaccination remains based on circumstantial evidence.

Placebo Side-Effects

As noted in the context of the CDC-published Pfizer-BioNTech study results, there were many side-effects reported in the placebo group as well, including significant symptoms like fever, diarrhea, and vomiting. This highlights a big problem not only with placebos during medical trials, but also as a corollary when people are administered the real medicine.

Fueled partially by media reports and things one may have read on social media or heard from friends and colleagues, the mere fact that one has been vaccinated can lead to symptoms such as nausea and pain. When you’re already looking for something to happen, you’re much more likely to find that thing. Exaggerated negative effects to a treatment or vaccine are generally referred to as ‘nocebo effect’, where the expectation of negative effects from the treatment (even if it is a placebo) can result in the patient suffering those effects.

The nocebo effect (or phenomenon) is becoming more the subject of studies, due to its effects on medical treatments and patient care, as reported by Winfried Häuser et al. in 2012. Especially noted here is the importance of communication with a patient about the expectations they have, and to adjust these accordingly. In the context of a world-wide vaccination campaign as is currently ongoing with the SARS-CoV-2 pandemic, one may also consider the impact that the (social) media has in terms of mass psychogenic illness (‘mass hysteria’).

Although clear communication to set expectations is attempted by medical health professionals and others, there exists enough disinformation via other channels that some individuals may have become convinced of the purported negative effects of these vaccines. Here the risk is that even in those who are not necessarily against getting vaccinated, they may still subconsciously project a subset of the negative effects they have heard about onto their own body, effecting a nocebo phenomenon.

Take a Chill (Sugar) Pill

As vaccines have become more refined and we understand better the effects and symptoms (desired and undesired) that they provoke in the body, they have become routine enough that generally we are barely aware of how they protect us. After our childhood vaccines the most we tend to deal with vaccines is when we need a booster for tetanus, or when we go to some foreign country that demands proof of certain vaccinations, or just to protect ourselves against specific diseases that are endemic there.

What the world is currently experiencing as a result of the SARS-CoV-2 pandemic is (so far) truly unique, in the sense that this is the first pandemic that we’re vaccinating against on a world-wide scale. Compared to the leisurely pace of the smallpox eradication program that took decades, the current goal is to get the entire world vaccinated in a matter of years. As a result of vaccinating so many individuals simultaneously on such a massive scale, even rare side-effects will occur more often on a pure cases basis.

Even so, for the overwhelming majority of people being vaccinated today, tomorrow, and in the coming months and years, a sore arm and possibly jittery sensations will be the most they will ever experience of this mass-vaccination campaign. All of which are merely natural signs of your body’s immune system doing exactly what it’s supposed to do.

85 thoughts on “Mechanisms Behind Vaccine Side-Effects: The Science That Causes That Sore Arm

  1. How can you go through all that and not mention adjuvants?

    These are nasty chemicals mixed in with the vaccine (not all or them though) that are known to provoke an immune/allergic response, and ‘get things going’ so when the body’s defence cells turn up they also tale a look at the vaccine active ingredients and assume that’s the cause of the inflammation.

    1. i could be mistaken but it’s my impression that most of the common covid vaccines do not use adjuvants. i think adjuvants are more valuable if the vaccine provides the antigen and the body needs to be provoked into attacking it. the mrna vaccines don’t provide the antigen, they provide rna that would cause the body to create the antigen. for reasons i’m unclear on, the body seems to attack that antigen without an adjuvant, perhaps because of how it is made within a cell (cells have a variety of mechanisms to invite immune cells to attack unfamiliar proteins that appear within them). i’m not as clear on the j&j shot but i don’t think it uses an adjuvant either?

      1. I watched a talk by a medical doctor who explained that many people would have an allergic reaction to the PEG in the mRNA jabs. As the serums are stored a stored at very cold temperatures it makes sense that antifreeze would be necessary.

        1. There have been cases of PEG allergy in individuals being treated with large amounts of IM/IV medication containing PEG over a prolonged timespan. I’ve not seen any cases for the minute exposure involved with C-19 vaccines.

      1. External or oral/digestive-tract use != intra-venal injection. (like poisonous!=venomous)

        PEG can be perfectly fine for skin contact or oral ingestion, but cause problems when injected directly into your veins.

        minute amounts of PEG injected intravenously isn’t a problem for the (vast) majority of people, but it’s not exactly sterile saline solution either.

        Most SDS sheets on PEG only list a dermal and oral exposure level, for which you’d need quite a lot of exposure for it to do anything and none of the effects seem to be long lasting.

    2. “How can you go through all that and not mention adjuvants?”

      It might have something to do with the fact that none of the 3 vaccines approved in the US have adjuvants. They don’t need it: both of them produce *easily* enough COVID antigens to piss off the immune system. That being said, the ones *outside* the US (Novavax, for instance) do.

      “These are nasty chemicals”

      Stay away from people, then, cuz they’re *coated* in those nasty chemicals! One of the most common adjuvants is squalene, which is one of the oils produced by your skin and in your hair. And the one in Novavax is saponin-based, which is often pushed as a dietary supplement and have been used for a *long* time.

  2. I shivered later in the evening after my first dose, but it might have been the cold and wet weather. Nothing the second time.

    But the first dose probably didn’t do much, too soon after the drug that I get every six months that diminishes my immune system. Abpnd I’m not talking steroids, though that impacts the immune system.

    The needle has to go deep, surely that accounts for sore arms. It had been decades since my last needle, until 2019. A pneumonia vaccine, after endless blood tests and infusions. They said it had to go deep, and it did hurt. And it was sore for a few days after. But it had nothing to do with the vaccine, just the needle going deep.

    For months in 2019, I was getting shots to the belly, blood thinner. Those were worse. Not only twice every day, but while not deep, the nurse had to pinch the skin. I was bruised for months. That was something I wanted to avoid.

    But when I was a kid fifty years ago, I didn’t like getting needles. Just the act of the needle going into the arm. But nobody talked about not getting vaccinated, or “bad” effects.

    I had my two Covid-19 doses. I belatedly can get a third (it’s too late tor me, and if the twodoses had been by my schedule, I might be better vaccinated). And I’m little or not protected.

    So it’s up to other people to make it safe for me and others like me. Because I never got back to normal after my 2019 illness, before the pandemic struck, it’s been 2.5 years since I was last in a bookstore, 2.5 years of not normal.

    1. “So it’s up to other people to make it safe for me and others like me.”

      Have been to every continent except Antarctica at least twice (does it count if I flew over the edge of Antarctica?). Have lived, for at least 4 months, in 15 different sovereign states, and have visited, for at least 9 days, over 40 nation states. Have seen humans try their best to do good things, but more typically, have seen humans either not care and not do anything at all, or do their best to do the bad thing.

      Your expectations would seem to be impractical and unreasonable. In general, it would seem that one cannot depend on humans to do the ‘right’ thing. There are probably a few individuals within your tribal boundaries that can be depended on’ otherwise, you are on your own and dependent on just yourself unless you have some source of power that will coerce others to do your bidding.

      This is similar to, and related to, the misplaced and almost fundamentalist belief that technology will eventually solve our problems.

      Good luck, and may the Goddess smile upon you and yours.

    2. Michael Black said: “I shivered later in the evening after my first dose…”

      I got two jabs of the Pfizer-BioNTech SARS-CoV-2 vaccine. The first shot came with zero side effects, not even a sore arm. The second dose brought on bone-breaking chills for two whole days, but nothing else, no fever and again not even a sore arm. My Mother who is 91 years young also got two Pfizer-BioNTech jabs. Neither of them bothered her at all.

    3. Lack of circulating antibodies in the blood does not mean you’re not protected. What happens with every infection or vaccination is the immune system reacts and produces antibodies. Once the invading organism is eliminated, the immune system stops producing antibodies. But the B cells “remember” the organism and if it gets in again, they’re ready quickly to produce new antibodies.

      This used to be taught in basic biology classes in late Grade School to early Jr. High or Middle School.

    4. I get monthly B12 injections in my arms. They hurt way more during the injection due to the formulation being a bit alkaline and needing an acidic buffer the make it neutral, usually acetic acid. The insertion of the B12 needle usually hurts more than both of my Pfizer injections did. I think the Pfizer used a thinner gauge needle. I’ve never had sore arms from my B12 shots but the Pfizer hurt both times, the first shot lasting longer. Also a few years ago I had some booster shots and the HPV vaccine hurt a bit, forming a big bruise that lasted two weeks. My doctor said it probably hit a capillary on the way in which caused the bruise.

  3. I got Moderna back in April, heard a lot of grumbling from older folks around me “My arm hurt!” But I blew all that off as wussy behavior, “pfft, I’ve broken over 40 bones between skateboarding and motorcycles. Sore arm from a needle? Whatever man” Next morning… yeah I was wrong, that was mos’def a painful sore arm. Was debating cutting my shirt off cause I couldn’t move my shoulder. Either it did hurt as bad as everyone said, or I’ve become a bit of a wuss in my middle aged years.

    1. As someone who also got Moderna (and your elder), I’ll tell you not that you a bit of a wuss but you had a irregularly strong reaction. I’ve heard people have minor pain or none at all but never anything as serious as what you describe. It’s likely that most grumbling was “wussy behavior” but there are odd fellows like yourself who have strong reactions.

      Just be glad this isn’t the polio vaccine or worse yet, the smallpox vaccine. Those were primitive and lot of people died from them compared to what we have now. mRNA vaccines are the future and will likely replace all “traditional” vaccines because of how safe and effective they are.

      1. I am struck with the notion that while the vaccines are ineffective on the immunocompromised, we are safe. If it introduced the actual virus, I think I’d worry that my immune system wouldn’t react, so I’d get sick. That can’t happen with mRNA, no actual virus involved. It just fakes the virus.

        The wonders of.modern medecine. We all now know more than we want to know on the topic.

        1. I understood the biggest danger about the virus is the delayed strong reaction, where the immune system has a big lag and then attacks the already compromised tissue with the fury of a thousand suns, at which point your heart or lungs fail.

      2. I got a sore arm both times from Moderna. It got painful enough to need a painkiller as it spread down to the elbow and wrist so I couldn’t sleep. The second time I got the shivers of my life with a temperature up to 39.2 C before I decided enough is enough and took ibuprofen, which made it go down.

        Last time I’ve been that sick was with pneumonia more than 20 years ago. Terrible stuff.

        1. In case of fever afaik it’s better to take acetaminophen/paracetamol (commonly Tylenol in the US I believe?). Ibuprofen is a low dosage inflammation inhibitor, but that MAY in this case be detrimental to the functioning of the vaccine and acetaminophen/paracetamol is more effective in lowering a fever temperature.

      3. I still have a scar on my left arm from getting vaccinated for Smallpox and a bunch of other things in 1978 before my family went to the Philippines. (I was 7 years old.)

        It was just a little jab barely through the skin for all of that.

    2. Interesting. I almost never get the yearly flu shot because of the arm pain, which typically lasts for 3-4 days and honestly has me on the verge of tears. I’ve had root canals, kidney stones, shingles and have broken bones so I’m not soft on pain, but I’m telling you, the arm pain I get from flu shots is unbearable. I work from home, so my risk of getting the flu are pretty low, and when I have gotten it, it’s been overall less uncomfortable than the shot.

      But with the Moderna vaccine, I had almost no arm pain at all, from either shot. Any pain I did have I would think was attributable to simple having a needle jammed through my arm muscle. Bit of tiredness after the first shot, and a mild headache and chills after the second. Even if it did have flu shot-type arm pain, I’d have sucked it up for the benefits of course, but I was very happy it didn’t.

      1. hmm, I usually get the seasonal flu vaccine and at most the area around the injection spot on the upper arm gets a bit stiff and sore for 1-2 days, nothing more.

        The last time the administering nurse suggest to kinda literally “rub it in” (massage the spot right after the injection). I did that and hat no soreness or pain what so ever.
        Immediately my guess was that the vaccine gets better distributed in the muscle, thus increasing “the surface area” for the immune system to react and in turn distribute the reaction too.
        -> instead of one localized strong and painful reaction it’s broader and not so strong (my thinking).

    3. It appears to be quite individualized. I know of several folks who have had reactions, though I myself had zero reaction — barely even any shoulder pain from the needle itself.
      As to what that actually means, who knows yet. It could mean that you have a distinctly active immune system. Maybe! It could mean that of all folks you really needed to have it because you would have reacted badly to the actual disease. Maybe! It could mean nothing at all. Maybe!
      But what is certain is that a couple days of sore arm are far less painful than forced breathing via ventilator. Well, at least until there’s absolutely nothing painful at all, anymore.

      1. There’s a great probability that you’ve already had the virus before your vaccination, which would explain a strong reaction. The early testing and tracking was so limited that the by now about a third of the population may have had it anyways.

        1. For a lot of people an infection with SARS-CoV-2 is no worse than any other cold caused by any other coronavirus or rhinovirus. They never know they had it. For some people, their symptoms may be worse than a typical cold, almost flu-like, but they never develop pneumonia.

          The ones who have to go to a hospital are the fraction of cases where the virus really hits their lungs hard.

    1. Pfizer here too. First dose gave me a weak arm for a day or two. Second dose made me very tired on the day, then felt like I’d been kicked in the head the next morning. No fever or anything like that. Felt fine by that night though after a day popping painkillers.

      Less injection site pain than a flu shot though.

      Having been kicked in the head before, this is an accurate reference.

  4. It cracks me up that many of the people I know that refuse to get vaccinated are smokers and drinkers.

    I had no soreness after the first shot, but felt a little achy the morning after the second. My wife had a similar experience.

      1. Did the tobacco companies fund that study?

        I’m aware of only one thing smoking is good for. Mosquito repellent. Many decades ago my uncle took me fishing and lit up a cigar. He didn’t smoke. I asked him why. He told me it kept the mosquitos away. I didn’t get bit.

    1. Sorry, but you are mixing facts and science, which is always a real danger.

      Smoking has proven to cause cancer unequivocally (without doubt), in multiple studies. If that’s not enough, there’s also plenty of empirical (statistical) and anecdotal (“I know someone”) evidence.

      Vaccines like mRNA are developed, not discovered, so we can say with certainty that we know what they do. However, it takes time to notice the far side effects. The immediate ones we can predict. But just think if you left a banana peel on the street and it causes a plane to fall out of the sky – you cannot immediately make the connection and it should not require that bananas are banned everywhere.

  5. The fever makes perfect sense if you understand that fevers are something your body does to fight infection, not something infections do to fight your body.

    I think calling the evidence of myocarditis circumstantial is inaccurate; there’s extremely good evidence for it, or at least as solid as you ever get when studying squishy, poorly controlled, living things. My mom got it before they even knew about the link and it was no joke. It took her months to recover. The infuriating thing is that it still hasn’t been reported to vaers, since the doctor insists it “might just be coincidence” (which obviously is technically true), but when a healthy person comes down with a rare heart condition *right after* being vaccinated, why would you not report that??

    1. You can get it twice. You might get a variant. You could still spread it to others. Better safe than sorry, I say.

      I would agree though that you are temporarily at a lower risk of the above, if you had it recently – but immunity wanes over time.

  6. first vaccine (i had moderna) didnt have any side effects for me, but the second one put me out for 2 days. arm never got sore. though i recently had a tetanus shot and that made my arm sore for a week.

    1. My wife too. She spent a day in bed with chills after round two.

      I got three days’ sore arm the first round, and then did a lot of stretching (some hokey German tele-gym thing, but man, it was pretty stretchy) the morning after the second round, and it pretty much went away.

      The joke about sociologists, as told among economists, holds here: “Data is the plural of anecdote.”

    2. i got the moderna shot had a very sore arm (I would compare it to being hit in the arm with a big stick) after both shots, and swollen lymph nodes after the second shot. Overall a small price to pay for protection against this deadly disease

    3. Bit of hangover feeling the next day after second dose but no fever. Was back at the gym after three days. But still three weeks as of yesterday I had a small pain in the arm doing overhead presses.

  7. No don’t jump on me as an antivaxxeer or anything, but I have a question, and this seems a place people could answer it. As the mRNA causes body cells to express the viral protein on their surface to bring the active immune system into effect against Covid could it not be possible that the immune system could also be sensitized against the cells (or some of their surface components) and cause an autoimmune disorder? Has their been any discussion on this, I know I may just be stupid but I’m still curious.

    1. If you are familiar with IT, you can search for “Reverse Engineering the source code of the BioNTech/Pfizer SARS-CoV-2 Vaccine” and you will get a lot of your answers there.

      Basically, most side effects should be reduced with an mRNA vaccine, compared to the viral ones, as only the needed information is contained in such a vaccine.

      As it’s usual with science, no answer is definitive, but in normal terms it should mean it’s much safer than anything we could come up before mRNA.

    2. it’s super possible for any vaccine, or really just about anything for that matter, to cause an auto-immune response. there’s definitely good reason to suspect that mrna vaccines in particular would have a unique role in the immune system. like how the j&j vaccine (and the wild coronavirus) can each cause your immune system to attack your own platelets (thrombocytopenia). run-away auto-immune responses also seem to be implicated in long covid, and the causative pathways are only guessed at at this point.

      the only reason we know it doesn’t happen (or, to be accurate: happens very rarely, or very mildly) is the large amount of testing that has now been done because of the huge sample size of immunized people. when they were doing the first rounds of testing last year they must’ve been crossing their fingers like crazy that they wouldn’t cause such an effect.

      it’s still possible that there is some sort of delayed auto-immune reaction, it might set you up to where a subsequent infection will trigger a stronger auto-immune response. with each passing day, it’s looking less likely (it would’ve shown up in mass statistics by now), but fundamentally you can’t prove it won’t happen until decades have passed. a lot of things in medicine can be predicted but a lot of it is just wait-and-see.

    3. Theoretically possible? Sure. But so is a massive immune reaction to the mRNA causing anaphylaxis.

      What I think you are envisioning is that a cell takes up the mRNA, makes the proteins, and then puts those proteins on its surface. The immune system then thinks “that cell is an invader” and not only attacks it but also becomes sensitized to that cell. If that happened, that would be bad.

      But the way I read the research, and the way the vaccine seems to work, one thing happens that is very different. The cells that make the protein don’t just stick the protein on their outer surface. The protein is instead released out into the body. So, ideally, the immune system sees the protein as an invader, and not the cells it is attached to.

      This does comes with different risks. One risk is that an immune response develops to attach a part of the protein that isn’t accessible on the virus. Free-floating proteins have the base “visible” for the immune cells to attach, and that wouldn’t happen when they are attached to a virus particles.

      Then there were studies that have shown that the protein alone could be the root cause of some vascular symptoms of long covid. The protein was being studied as the cause of organ damage to the kidneys; since the virus didn’t appear to be making it that far, yet people are still having those issues.

      However, the amount of proteins produced by the vaccine is orders of magnitude less than what an infection would cause. The risk from the virus is still many, many, times higher.

  8. My arm was getting stiff within a few hours of the second shot. Figured that would be it. My body decided that moving my arm was overrated, and decided that a low grade fever wasn’t enough of a response.

    38°C by sundown, and not able to move my shoulder for most of a week. Fever stuck around for five or six days, too. I’m pretty sure my body knows what this protein “looks” like and is ready to kill it if we ever encounter it again.

    And yes, five days of bed rest is still way better than risking a ventilator.

  9. I don’t have (big) issues with pain and don’t recall ever having side effects. But the first Moderna put me out of order for one week, the second one just for a few days. I was really anticipating that nothing would be felt, but I was wrong.

    Might be family related, had another 2 persons in the bloodline experience serious side effects, one Moderna and one Pfizer. So might be something linked to genetics and the immune system. Everyone else had a jolly time breezed through.

    The only reasonable explanation I’ve gotten is that, the 3 of us, were previously infected, causing the immune system to ramp up unreasonably high.

    I’m sure we will see later studies on side-effects and I encourage everyone to submit their side effects to their local authority, most governments have such a program in place.

  10. I got both Pfizer shots and my reaction to both was exactly the same as getting the flu shot (which I used to get almost every year) — my arm was a little bit sore for 1 day (not painful at all). People have different reactions, but most of the people I know that had a stronger reaction (arm pain that hurt when touched or nausea or fever) are women. At first, I was wondering why women tended to have a stronger reaction to the vaccine. But then I listened to a podcast that was talking about how women tend to have a move active immune system and it’s the reason they are more likely to have autoimmune diseases like lupus, rheumatic fever, multiple sclerosis, and some others. I found the podcast interesting because it mentioned that when women get pregnant, it usually helps with symptoms of their autoimmune disease.

  11. I lost my father and cousin (on father’s) side to Covid, so I wonder about a genetic susceptibility to it. So I took a calculated risk in getting the vaccine.

    I got both doses of Moderna in June, the 2nd dose of which I have had a very bad reaction to

    I had a splitting headache for 21 days, with fever and chills daily for 16 days. For 5 days, I lost all sense of taste except for salt, which was amplified. All appetite was lost for 4 weeks, so I just ate to stay alive without any desire for food. Tinitus, body aches, extreme fatigue and weakness.

    Now on day 73 of a continuous sore throat, and have been having debilitating pain, swelling, and immobility in joints that rotates between which joint it is affecting. All this has been accompanied by a rash on arms, legs, torso, and jaw, and severe itching that prevents sleep.

    Doctors say there is nothing that can be done.

      1. I asked the doctor about that… He basically ridiculed me for suggesting that… But then, he was spouting political ideology as he walked onto my room with the nurse (VA healthcare… options are slim).

    1. Sorry to hear form your condition. I agree with Gregg’s suspicion, but there does not seem to be a lot of knowledge of vaccine – infection interactions, only that a stronger reaction to doses may be linked to prior asymptomatic infection.

      As for what could be done, I can only point you towards the research done by Bruce Patterson:
      They seem to have tentative evidence for Long Covid therapy options, but it’s not widely reported and pending further studies and proof.

    2. If you’re genetically predisposed to a bad COVID reaction, you’re probably also predisposed to a bad vaccine reaction. They do after all share immunological characteristics. I suspect, and hope, bad luck with the vaccine means you probably dodged a bullet with the disease. Genetic suseptability is a fact, look at CDC data, for some reason the Vaccines appear to be particularly ineffective amongst the Inuit.

  12. My Wife and I both went together and got the Pfizer. Only slight sore arm after the first one. She only had mild fatigue after her second, (on Aug 9’th) but the next day I had a slight fever and the general “BLAH” feeling that goes with it. Funny thing is, I guesstimated my fever as 100 degrees, just based on how I felt. Got the thermometer… and sure enough, my temperature was 100.1 degrees! LOL! :) I thought that was pretty good guesstimating, and so did my bride. :) Anyway, my overall time of feeling “slightly unwell” lasted about 48 hours, and then was gone. We’ve both been 100% fine, since. :) Also, everyone we both know, got the Pfizer. Their reactions were like ours… mild “unwell” feeling, then back to normal. I’m glad we got it “out of the way”.

  13. After my first dose of Moderna vaccine at 11:30 AM I was feeling tired by evening. Still fatigued the second day and had chills and shivering that night. Day three I was feeling better and the injection site soreness was fading. Day 4 went downhill quickly. Apparently I already had SARS-CoV-2 in me and symptoms kicked in just as the vaccine effects were getting finished. (Amusing side note, I noticed beside the chair I sat in for the injection was a Dewar flask that had a label on it mentioning bovine reproductive material. Apparently there’s a shortage of such containers for storing the vaccine and someone had to borrow at least one from elsewhere. I assume it was very well cleaned before putting vaccine vials in.)

    Long story short, after about a week and a half of feeling like crap, my taste sense going wonky (but not my sense of smell) I got to where I could barely breathe so I had a friend take me to the local ER. They put me on oxygen and drained a whole bag of saline into me. A covid test came back positive and after being there a couple of hours a bed was found in a hospital in the capital city. I noted the times of departure and arrival, took exactly one hour by ambulance, without lights and siren.

    I was on 5 liters per minute of oxygen on Wednesday and by Sunday evening was off oxygen then sent home Monday afternoon. Recovery of strength and stamina has taken nearly a month, complicated by a non-critical medication I was prescribed while sick but I didn’t start taking until getting out of the hospital. My body selected dizziness, coughing, and throat swelling from the med’s long menu of of *possible* bad effects. Took about a week (as usual for me if it happens) for the problems to occur and around five days to go away after I quit taking the med.

    After I got home and read through my records I saw that when I walked into the ER my blood oxygen level was down to 70. Normal is over 90. When I tell that to medical people their eyes tend to bug out. Apparently most people with a BOL of 70 aren’t walking anywhere.

    I got the second dose of Moderna vaccine after getting out of the hospital and the effects were pretty much identical to the first dose, except the injection site hurt more and took a week before all soreness went away.

    If your taste sense is still wonky, try this. Brush your teeth and tongue with cinnamon toothpaste (I used Crest brand) and swish all round your mouth. After spitting that out, take a whole capful of original Listerine and swish it around. Hold it as long as you can stand it before spitting it out then rinsing with water. I just had the idea to try mouthwash to see if it might have any effect on my sense of taste. Dunno why I used the cinnamon toothpaste first, or if it made any contribution.

    If you’re allergic to Eucalyptus you most likely do not want to try that. Listerine has some Eucalyptus stuff in it.

    For me the results were immediate. My taste sense had “gone blind” to some things while making some other things almost vomit inducing. What was odd is that chocolate wasn’t affected at all but orange was intensified – except for actual oranges and orange juice tasted “flat” because I couldn’t sense the bite of ascorbic acid. My umami (the taste that MSG and other savory stuff triggers) sense was flat out gone.

    First test was a piece of honeydew melon, which before the toothpaste and mouthwash tasted like nothing. Ding! Delicious! I literally cried happy tears. I went on a bit of a binge trying foods that I either couldn’t taste or had tasted terrible. Much of it that I couldn’t taste had at least some flavor, and there were no more mis-tastes where something tasted awful. Umami/savory was still completely absent. Real orange was still blah but orange like a creamsicle was still extra intense. Even water tasted completely wrong. This was a few days before the pneumonia hit me.

    Food at this hospital was very good. Meatloaf, grilled chicken, pork shoulder, baked salmon, fresh fruit, vegetables perfectly cooked. The only horrible dish was the first evening when they brought me “Zoodles” and butternut squash ravioli. I didn’t need effed up taste sense to know that was disgusting. After that, food services called my room each day to ask what I wanted for dinner, and for breakfast and lunch the next day.

    Currently, I’d say my sense of taste is almost back to normal. Umami/savory has re-awakened, I can taste beef jerky again where a couple of weeks ago it had no flavor at all. Orange still tastes extra good, which reminds me I have some Creamsicles in my freezer.

  14. An omission regarding injection site muscle, and other pain and effects is that the vaccination may have been done improperly – needle too deep – needle not at 90 degree angle – inadequate cleaning of the site – patients not advised to abstain from aspirin, etc., prior to vaccination – an improperly placed needle not going into the deltoid muscle as required – patients not advised to hydrate to up electrolytes, following vaccination…

  15. estimated 1.5 billion may not be needing electronic projects any more. others may rely on them and some of us to construct such projects. business opertunities folks. overstock should drive costs down. do some research. brings to mind the GMOs. watch out for probable replacement, Mrna modified veggies. mmm mmm mmm , eh? i think ill go check out some more of these cool projects here. be well all..

  16. “Fueled partially by media reports and things one may have read on social media or heard from friends and colleagues, the mere fact that one has been vaccinated can lead to symptoms such as nausea and pain.”
    Virus itself effects could also be influenced this way could it not?
    I don’t trust the testing numbers purely on a singular incident, I will admin data point of one is not useful. A few family members scheduled to get tested, leaned when they arrived they would have to wait an hour, and left without getting tested. 3 days later they learned they were positive…

  17. From Australia here. Most of our vaccine has been AZ AstraZenenca, more recently renamed to Vaxzevria, probably for marketing reasons (see below). Currently there is plenty of AZ which is made here. The alternative has been Pfizer which is in chronically short supply. I could not see a mention of AZ anywhere. Moderna is a late comer.

    IMHO Australias management of Covid has been a debacle, but I think perhaps not as bad as USA. (Over hysterical reaction to virus with extreme lockdowns leading to protests then full blown riot response with batons, police horses, rubber bullets and all. On the other hand vaccination has been laxidaisical, inadequate and just plain incompetently managed. Then we got stupid advice against AZ, quickly retracted, but that put people off getting vaccinated). Sadly I could go on but I will restrain myself.

    Anyway AZ has a major complication of clotting (in the 1/100,000 level). There is often a mild injection side reaction. The second dose has a lesser reaction. I spoke to a vaccinator who said that Pzifer seems to have a milder first reaction but often a quite strong second dose response. Only anecdotal, of course. I have had 2 doses of AZ. No problems at all.

    AZ seems like it might be a relatively dirty vaccine, grown in a killed adenovirus I think so we might expect more cross reactions.

  18. Most people I know that had Pfizer had at most severe arm pain after their fist shot and a mild fever-like symptoms after the second shot, and almost everyone said the second shot was worse.

    For my first shot of pfizer I felt my arm the day after, but nothing serious. I didn’t notice any real side effects for 6 days, but after that I felt like I had drank too much the night before (not a real headache, just a general “under the weather/cotton in my head”) feeling, with decreased concentration, that again lasted for a week. I was about to call my doctor when it dropped away.
    I have heard of one person since that had a similar reaction.

    I biked to and from my second shot, 35 km with strong headwind back, so I had some muscle pain in my legs and a little sore arm, but no other effects at all from the second shot.

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