• Welcome to Phoenix Rising!

    Created in 2008, Phoenix Rising is the largest and oldest forum dedicated to furthering the understanding of, and finding treatments for, complex chronic illnesses such as chronic fatigue syndrome (ME/CFS), fibromyalgia, long COVID, postural orthostatic tachycardia syndrome (POTS), mast cell activation syndrome (MCAS), and allied diseases.

    To become a member, simply click the Register button at the top right.

delayed reaction to pfizer vaccination anyone ?

apologies if theres already a thread about this.

I felt pleased with my reaction to my Pfizer shots in September and November, just 48 hrs of light fever. But in the last month my energy has trailed down to a new low, and my muscles are shakey and my concentration is zero.

Of course, with ME there can always be so many reasns for a relapse - and its ben a tough year in many other ways that could also explain this. but has anyone else reported doing fine with their covid vacinations, and then deteriorating like this several weeks after having them ?

thanks for listening


Senior Member
United States, New Hampshire
Of course, with ME there can always be so many reasns for a relapse - and its ben a tough year in many other ways that could also explain this.

I've not had the vaccine, because I got covid in October. But my guess would be it's probably more related to the other stresses in your life. The reason for my thinking is that I think those of us that get a bad reaction to the Covid vaccine get it because we already have "sensitized" microglia.

ME/CFS researcher Jarred Younger thinks that these sensitized microglia in the brain, are causing low grade inflammation and ME/CFS symptoms. As I understand it, anything that significantly increases the immune system, can further sensitized these microglia, making symptoms worse.

My feeling is that should happen pretty fast after the vaccine though, if that was going to happen. I don't know if it would happen many weeks later.


Senior Member
U.S., Earth
Yeah, it's always hard to distinguish cause-and-effect when there is a time delay between the cause and the effect. This is why it is easy for new people with ME to fail to notice the link between their exertion and the delayed PEM that comes two days later.

I also had mild effects for about 48 hours after the Pfizer vaccine. 1.5-2 weeks after the vaccine I developed gastrointestinal inflammation which lasted for 1.5 weeks or so. I didn't associate it with the vaccine until the same thing happened after the second vaccine, and then again after the third. A weird effect, but it was temporary each time...

Rufous McKinney

Senior Member
My husband experienced a staph skin infection, reactivation one week after his J and J shot.

I got a possible reactivation about two months later, my stomach/vagus has a critter residing there it seems.

He did not get any evident reaction to getting a dose of Pfizer .....after his first J and J...


Senior Member
United Kingdom
Have actually heard a few people describe what your describing.

My energy levels do seem to be slowly stabilising. But I think (hope) I'm simply in the winter period of discontent. Low temps, lots of colds and viruses and constantly sick. Or the mRNA booster seriously did me some damage. I won't really know either way until April when the heating goes off in my house and my body can return to a state of semi normality. Instead of full on immune assault.

Even so why the body goes down like this instead of returning to recovery is anyone's guess. Plenty of reasons.

I do hope you are able to get some small vestige of activity out of your day though even with this new setback. All the best.
thanks everyone for these great replies. I feel like I have a good range of coping stratgeies to fall back on duing flare up time - though my anxiety and paranoia shoots way up after activity, which I really hate. Still, with covid levels high in the UK, I had no plans to do anything in February/March anyway! So just rest ... rest ... rest and see what happens. Thanks again for sharing your different experiences.

vision blue

Senior Member
This is my stuff of nighmares. And why im living like a prisoner rather than getting a vax for as long as i can hokd out - for the possibility of delayed reaction and setback. My worst reactions to illnesses are well after. For respitory infrctions , 3-6 weeks after and for vertigo triggers, can be 6 mo after the event

Will wish for your speedy recovery with extraspecial vibes if its from the vax

How about trying a state chager of some sort? Give yourself an allergic rection or a bee sting or a cut- something to jar ykur immune system away from whateverit’s doinf

Curious where youve seen that discussion of others with delayed reactions. And hopeylu cqn update us in april.
Last edited: