Reaction to AZ vaccine, GP wants 2nd dose to be Pfizer

[Kittypillar]

Had my 1st dose of AZ back in March. Seems it didn't agree with me and about 10 minutes afterwards I had a reaction (swelling in my throat, went very wheezy and for nearly a week afterwards felt like I was trying to swallow a golf ball). Antihistamines did help and otherwise didn't have any other of the usual side effects except for a bit of a fever and feeling shivery.

Having spoken to my GP about it at the time and them having consulted the allergy service, I've now found out they are recommending my second dose be Pfizer instead, as they're worried second time round the reaction could be worse.

Unsure of how I feel to be honest - I'd obviously not want to have the same reaction (or worse!) again but it seems to be frequently described as "optimal" to have the same type of vaccine for both. Digging around on the internet for factual information on how it might effect efficacy and can't find anything that isn't speculation... Am I just not looking hard enough, can anyone signpost me to the something valid (I know other countries are mixing dose so surely there should be data to support that?)... Or do I just need to go with what my GP says and wait for the results from the studies going on right now to find out? Also waiting for a call back from my doctor (I found this out as got a call from the vaccine booking service) but wondered if anyone here could help in the meantime.

Do you know what you are allergic to, and is the decision based on the vaccine ingredients? You can look up the ingredients for each online.

@MRex I have absolutely no idea! I've only ever had a reaction to eating mussels before and I'm pretty sure that wouldn't be in the vaccine ingredients list. I'll definitely ask my GP about this though, decision afaik is purely based on the reaction, the time it happened and the fact that when I was told to take antihistamines it helped somewhat.

Could you ask about allergy test? The most common allergic reaction for the vaccinea is to PEG (Pfizer/ Moderna), and some people have a reaction to Polysorbate 80 in Astrazeneca, but some unlucky people have an allergy to both as there is some slight connection. Or it could be a random ingredient and then you're better to have Pfizer, but at least you'll know why.

@MRex thank you so much, that's really helpful! Will definitely ask when I get to speak to my doctor. 2nd dose is due very soon, I wonder if that's why they're just saying to have the alternative vaccine and not trying to figure out exactly what happened and why

I literally just read about a German study who studied the reactions and efficacy of having AZ as the first jab followed by Pfizer as the second, and the results are that both, reaction and efficacy are comparable to having two Pfizer vaccines.
I cannot find a version of the article in English but here is the link to the German one

https://www.spiegel.de/gesundheit/corona-kombination-von-astrazeneca-und-biontech-laut-studie-wirksam-und-gut-vertraeglich-a-b6327c72-80d9-423f-90c8-fe049fbcec99?saraecid=sociiupdKsBF0AFjflf0DZCxpPYDCQgO1dEMph

Thank you so much @Puffthemagicdragongoestobed! This definitely has made me feel less worried about whether it might put me at a disadvantage. Hopefully I fare better with Pfizer this time around!

My dh is having second dose Pfizer this weekend- first dose he had was AZ. He had a stroke (totally out of the blue - very fit and healthy) 2 weeks after AZ and has blood clots on his brain. GP suggested having Pfizer. He's been told they don't really know how well he'll be covered against Covid etc...
Hospital didn't think it was due to Covid, just a coincidence, but he decided he didn't want to risk it.
Hope it works better for you this time!

OP can I ask why on earth you’re considering a 2nd dose when you’ve had a bad reaction to the 1st?

@timetickson was the stroke due to the AZ vaccine?

Is your husband now ok?

I don't think there's any reason to think the effectivess would be less, they just haven't finished the studies yet. It does appear that the side effects might be more that with the same vaccine, but of course not necessarliy for everyone.

@timetickson so sorry to hear about your DH, hope he's recovering well now

@goodmorningsunshine7 I don't think I'd go against GP advice and obviously if their recommendation is Pfizer this time (I'm guessing their concern is anaphylaxis), then I'll go with what they deem most sensible. I think my only concern is whether it will potentially mean I'm not as protected from Covid in the future and I'm just trying to gather any facts on that if I can.

I wouldn't have any concerns about being less protected, results from other studies look promising so far. The only thing I'd want to check first is any additional PEG allergy risk.

@MRex definitely would want to find out exactly what it is I reacted to. Apparently doctor is ringing me this afternoon so I'll ask if it's possible to test to figure it out. They've been really helpful about the reaction I had so hopefully they'll agree. Definitely reassuring that studies are looking positive, thank you!

@Kittypillar

This article is about a Spanish study on mixing the two:

www.nature.com/articles/d41586-021-01359-3

It all looks good, and it seems that virologists aren't surprised as it's the expected result. It also states that the technique of using a different second vaccine to give a stronger boost to the first is already used when vaccinating against Ebola, so it's not even 'new science.'

@Kittypillar GP’s are not gods. It’s your body your health you are the one who should take responsibility for it IMO.

I am not medically trained, but my doctor said I could only have Astra Zeneca due to an explained allergic reaction mainly years ago. The mass vaccination centre wouldn't give me the jab and I had to have it at the doctors surgery (was supposed to be in a hospital). They said I couldn't have Pfizer as it caused more allergic reactions than AZ.

Sorry you had a reaction OP. I had my AZ vaccine just over a week ago and have felt really ill ever since with some weird ear pressure thing and throat problem.

As far as efficacy against covid goes ALL the vaccines are pretty much the same. They differ only really in their delivery method -how they create the spike protein for the immune system to attack. Perhaps differences in how successful they are at delivering this, reflects in the differences in reported efficacy.

The main issue (and it isn't huge) with mixing vaccines is you're potentially doubling the side-effects. If you don't react to "A" once, then you almost certainly won't react the second time either. But if you had "A" followed by "B", then you have two chances of getting a reaction....

So I wouldn't worry. Your protection will almost certainly end up just as good as someone who had two jabs of either vaccine.

@goodmorningsunshine7 I am taking responsibility, hence the trying to find legitimate sources to answer my query on efficacy with mixed doses. But ultimately I am not a doctor and so I'm wanting guidance in this decision from one. Is following advice on something medical from someone who is actually medically trained odd nowadays? Are you baffled why I'm having a 2nd dose of anything at all, even a different vaccine?

You had what sounds like an anaphylactic reaction. I would carefully consider whether to have either of the 2nd doses (if you go ahead I’d have them in hospital if possible). and discuss with an allergy specialist if possible. Did you seek help at the time for the symptoms?

And if you did see a gp at the time and they advised antihistamine for throat swelling and wheezing rather than adrenaline and emergency treatment then I wouldn’t trust them to know the slightest thing about allergic reaction and wouldn’t listen to a word more they have to say on the subject.

Sorry to hear you've been feeling really ill since your AZ vaccine @goldenlilliesdaffodillies, really hope you start to feel better soon. Is your throat problem like a sore throat or does it feel more like swelling? It wasn't a nice feeling and I struggled to eat for the best part of a week with it, but it did ease off thankfully.

That's interesting about the reactions being more likely with Pfizer than AZ, definitely something I'll ask about. Unfortunately I missed the call from my doctor this afternoon and she wasn't able to ring me back before the weekend, so I'm hoping I can speak to her early Monday to clarify. At least it gives me the weekend to plan any questions I might have.

The research coming out now suggests that mixing doses is looking like it's safe and effective, I am surprised though they'd recommend Pfizer given that people with allergies have widely been advised to have AZ.

@Kittypillar - regardless of what your GP says, please discuss it with the doctor at the vaccination centre, they have a protocol to follow to keep you safe.

@Dingleydel I reported it to the person at the clinic where I had the vaccine, and they kept me there for half an hour. When it didn't get considerably worse (no rash or visible swelling then) person I spoke to at the time told me to take antihistamines and go home, report back if it got any worse immediately and for my DH to keep a very close eye for the next hour at least. Antihistamines improved it slightly but I was still struggling to eat so I went to out of hours at the weekend when it hadn't gone away. The doctor I saw then (not at my usual surgery) took tests to check my thyroid but those all came back clear. I think whoever I saw seemed to think it was a coincidence and something else was just going on at the same time. My usual doctor felt that was a bit of a stretch!