[Astrogazer (OP)]

My wife and I have had our COVID AZ vaccinations.   My wife felt cold and ill the next day and off her food, and she had a large red and sore area on her arm a few cms below the injection point for more than a week afterwards.

I had virtually no reaction to it at all.  No soreness at all, not that hungry the next day, but I expect that I was empathising with my wife.

1.  What is the body reacting to in the AZ vaccine?  With no real virus being injected, is it the body’s marshalling of the antibodies which makes us feel so ill?   The AZ vaccine uses a modified monkey flu virus I believe, is it this virus which attacks our bodies that makes us feel ill?

2.  As I had no real reaction to the vaccination, is my immune system primed for a real SARS attack as well as my wife’s?

3. When we get the second dose, can we expect the same reaction for both of us as we got before?

4.  Two people I know had their vaccinations two months after they caught the real Covid virus and were both ill for two weeks.  They had a similar reaction to the vaccination as my wife had, I’m wondering if the reaction is caused by the body reacting to the injections of more spike proteins, the monkey virus or something else.

[Bored chemist]

It's not what most people expect, but what makes you feel bad isn't the virus.
The feeling tired, achy etc is due to the body's immune response. (It's one of the effects of interferon)
And the vaccine does trigger that.
In some people, the effect is stronger than others.

If you are worried you should contact the NHS helpline and/ or your doctor.

[evan_au]

In some people, the (immune response) is stronger than others.

You could imagine that people who have had a previous & recent infection of SARS-COV2 would have their immune response primed to detect the SARS-COV2 spike protein.
- Their immune response will be quicker and stronger than someone who hasn't been previously exposed to the SARS-COV2 virus
- There is debate about whether people who have had a previous SARS-COV2 infection actually need the second vaccine shot. More evidence is being collected about this.
- The problem is that most/many people who have had a SARS-COV2 infection don't actually know, as most cases have little or no symptoms, and many people were not tested while they were infected.
- So the default treatment will be to get both shots of the vaccine anyway.

[biologybrain12]

Hello everybody.
The reaction to the vaccinations vary very very much. I saw it in the cases of my family members and some friends of mine. My dad and a good friend were both vaccinated with the same vaccine, but while my dad did not feel anything after the vaccination, my friend was very ill for one day.
This showed my that the reactions are totally individual...
Thank you very much for your explanations and reasons for this phenomenon.

[CliffordK]

1.  What is the body reacting to in the AZ vaccine?  With no real virus being injected, is it the body’s marshalling of the antibodies which makes us feel so ill?   The AZ vaccine uses a modified monkey flu virus I believe, is it this virus which attacks our bodies that makes us feel ill?

The AstraZeneca vaccine does inject a chimpanzee andenovirus that can infect cells, but doesn't replicate.  So it is a "real" virus.

Your cells then use the DNA to create a spike protein antigen which is immunogenic. 

Have you both gotten a single dose, or multiple doses?

Your immune system could react to either the target antigen (spike protein), or the delivery method (chimp adenovirus), or even preservatives in the cocktail.

As long as you have some response, I don't think there is any reason to believe you aren't immunized.

Perhaps a harsh early response would be a sign of reacting to the delivery method, and not the actual COVID spike antigen.