Why do some people have side effects to vaccine

[Teenageromance]

I’m curious about the science behind this. I had my first vaccine at the weekend and have felt dreadful. Aches and tiredness - not had Covid as far as I know. My 80 year old mother sailed through the vaccine. Why are different peoples immune systems responding differently?

Younger people and women are affected more.

Fb 67 no side effects
Sil 63 headache
Dh 62 headache
Me 57 every single bloody side effect, wiped out for 2 days😲
Ds’s ECV friends in their 20’s wiped out for a week!

Because that’s the nature of immune systems - they can vary remarkably from person to person.

Genetic liability, other conditions, current health status (i.e, having mild infection you're not aware of) and potentially a previous COVID infection can all make people respond differently to vaccination

Important to note that while there's lots of anecdotal evidence on which groups may be impacted more, there's nothing robust published yet (as far as I'm aware)

@Ninkanink

Because that’s the nature of immune systems - they can vary remarkably from person to person.

Yep. This.

@Ninkanink

Because that’s the nature of immune systems - they can vary remarkably from person to person.

Peoples immune responses appear to be inextricably linked to their genes. It's my DBs specialist area of research and what he did his PhD in. There's a notion that we might be able to "type" peoples immune systems much like their blood groups to help better with the right medicine for the job.

Funny old world. 500 years ago, doctors treated people as individuals, not bundles of tissues. Then we had the enlightenment, and disease follows tissues and dismissed the personalised medicine as nonsense.

Now we're edging back to it.

Yes it’s fascinating isn’t it!

I’d say I had a strong immune system - not had a cold or flu for years. So why would I react strongly to the vaccine?

Why do colds affect people differently??
Practically all of the symptoms you experience with a cold are due to your own immune system's response to the virus, NOT the virus itself.

It's like when you fall and bruise your leg - you get localised swelling and heat - THAT's your immune system busy fighting a non-existent invader - it's why you are told to ice bruises and sprains EXCEPT where the skin is broken when there may actually be an invader (i.e. bacteria can get in).
Your immune system triggers lots of things in the body, many of which have nothing to do with the problem at hand, but over time, it's proven evolutionary advantageous for it to react in certain ways and it's not smart enough to figure out ALL the variances of any particular situation.

So the reaction to the vaccine, is because it THINKS it may be fighting a virus, so it ramps up all the defences - takes it a moment to realise there's nothing to fight.

For me it exacerbated an existing ache in my knees. For one day only. For a cousin with a niggling lower back ache due to being desk-bound for 20 years, it made that worse. For one day only. To me, that suggests we might feel it where we have pre-existing inflammation.
For others it may be different.

Presumably because you have a strong immune system your immune system is reacting strongly. Your body has had the mRNA of a virus injected, your body is attacking it as it would a real live virus. When we're ill it's our own immune response that makes us feel dreadful rather than just the virus.

No idea. I had mine in the morning. About 12 hours later, I felt just like I did with flu but without the cough, those chills and sweat. Lasted for nearly 2 days. Then was wiped out a day after that. My arm was so to lift for an entire week.

I'll be going in for my second dose when called.

I think you have to include that one persons account of how ill they are is up for interpretation. DP and myself had it on the same day and I knew he was going to be more ill. I told him that most people think that tea tastes disgusting for 48 hours as I also knew there would be lots of requests from his sick bed. One cup of tea and he found it disgusting so I at least stopped that.

@Ninkanink

Because that’s the nature of immune systems - they can vary remarkably from person to person.

Yep, agree.

I may be talking crap, but my understanding is if you have a stronger immune system you mount a stronger initial immune response to the vaccine, meaning you possibly suffer more side effects. I thought this was part of the reason why so many young and fit people died of the influenza in 1918, it was the body’s massive immune response to the virus that actually caused death. Older folk and children with weaker immune systems were less likely to die.

I had zero vaccine side effects from either Pfizer dose, but looking back I was incubating the virus when I had the first vaccine, and obviously had circulating post-infection antibodies when I had the second vaccine so my immune system was already primed as it were.

I had a runny nose and slight cough too!

It all went though

Me 40: no side effects other than slight sore arm
DH 45: zero side effects
Parents 63&67: zero side effects.
Sis 30: zero side effects.
None of us have underlying health issues either.
I usually get cold and flus really bad and was expecting some side effects, but was pleasantly surprised.

A friend asked me the same question about an hour ago. She had the AZ vaccine on Sunday. Felt sick and fuzzy headed but not enough to stop her working. I had mine yesterday. Apart from slight ache in arm at the injection site I've had no side effects. DH had the Pfizer one at the start of Feb - no side effects for him either. Others that I know have had high temperatures, aching limbs, headaches, shivering starting 12 hrs after the jab but only lasting a few hours. I guess everyone's body responds differently in the same was as people have different effects of Covid.

I don't think there's any rhyme or reason. I've heard things that make the chances of side effects higher are: female, younger, had covid before, good immune system.

All these apply to me and I didn't get any side effects. Thought I'd be ill.

Me 52, bit sicky, slightly high temperature. Head ache, fatigue but I have fibromyalgia and god knows how my body responds to most things.
Nothing for first 24 hours. I'm 48 hours in.
Oxford Astra zenica.

I had mine six days ago and I still feel unwell. I am hoping it wears off soon as I am fed up now. I’m mid fifties with autoimmune issues so maybe my immune system has reacted too strongly ?

Younger people have more active immune systems.

Also a large % of the country has had Covid. Your immune system is much more likely to react in a flu-like way to the spike protein that it recognises.

Feeling poorly for 24hrs is a good sign, not bad.

Parents both 83 - no side effects
ILs mid 70s - no side effects
SIL early 50s - flu like for 48 hours
Twin B and me mid 50s - no side effects
DP early 50s - no side effects yet but only 5 hours in
All AZ

The same reason that some of us have asthma, hay fever, animal allergies, eczema, peanut allergies etc etc, and others don’t.

The human immune system is complex and varies enormously between individuals. The reasons for this are only partially understood. This is one of the many reasons why drugs, vaccines etc are tested on thousands of people to ensure they are safe.

If I get the AZ vaccine, I would expect to have side effects, because that’s just what my immune system does. DP had none, because that’s just what his immune system does.

I did only get sore arm from Pfizer. I don't usually get any side effects from meds/vaccines.