Astra Zeneca - 3rd dose or booster - risk of blood clots - any studies?

[marigoldflower]

Hello All,

My DH will probably be advised to have the AZ booster rather than Pfizer of Moderna. He had the first two AZ doses with minimal symptoms so he is ok with this.

Does anyone know if there have been any studies or can link to articles to whether the risk of blood clots is still present with a third AZ vaccine? i.e. if you have had no blood clots with the first two doses, then it's more likely that you will have no serious side effects with the third?

I remember reading that some had blood clots 14 days after the second dose (so presumably you are running the same risk every time you get a shot, or is the risk somehow lessened?)

I was wondering as the whole topic sort of 'resurfaced' this week as scientists apparently found what triggers this side effect (which I know is rare) and I was wondering.

I wish things didn't move so fast and there was more time to take everything in!

www.bbc.co.uk/news/health-59418123

AstraZenica is NOT being offered as a booster only Pfizer or Moderna:

www.gov.uk/government/publications/covid-19-vaccination-booster-dose-resources/covid-19-vaccination-a-guide-to-booster-vaccination

AZ has been authorised as a booster for those who cannot have the mRNA vaccines, I believe. I know I'm only one person, OP, but I've had 3x AZ and all fine.

Thank you dollywoodlooksgood it's reassuring.

HelenRose thanks, I will ask him to reconfirm, maybe he misunderstood

From the Green book, chapter 14a (the "bible" for Covid vaccination):
Reinforcing vaccination
The JCVI have advised that a full dose (30µg) of Pfizer-BioNTech vaccine or a half dose (50µg) of the Moderna COVID-19 vaccine should be offered as a booster dose irrespective of the
vaccine used for the primary course. Both vaccines are suitable for boosting adults aged 18 years or over, with Pfizer BioNTech preferred for those aged under 18 years. Both vaccines have been shown to give good immune responses in those already primed. (Munro et al,
2021, Choi et al, 2021). The half dose of Moderna and is expected to have a lower rate ofside effects (including myocarditis) than a full dose.
Where mRNA vaccines are not suitable, for example domiciliary vaccination for housebound patients, AstraZeneca vaccine may be considered in those who had received at least one dose
of this vaccine previously. In exceptional circumstances, persons aged 40 years or over who received a mRNA COVID-19 vaccine previously may be offered a booster dose of AstraZeneca
Vaxzevria vaccine following a decision by a health professional on a case-by-case basis.

I had AZ for first 2. Got Moderna booster. Minimal side effects, a day of low fever. Grateful as hell to have it.

Sorry to Hijack bit how can someone who had AZ first dose get a Pfizer or moderna second dose ?

Vaccine centres all refuse saying second has to be same as first

how can someone who had AZ first dose get a Pfizer or moderna second dose?

You are correct. It would be the 3rd one (or booster) that would be different, not the 2nd dose.

Thank you Cookerhood

*Sorry to Hijack bit how can someone who had AZ first dose get a Pfizer or moderna second dose ?

Vaccine centres all refuse saying second has to be same as first*

My DP got a Pfizer second dose after having AZ as his first. It wasn't because he had an adverse reaction to AZ, he just didn't want it after all the cases of blot clotting came out. He had a thorough discussion about it at the local walk-in centre who allowed him to have Pfizer as his second jab. So it is possible.

www.bbc.co.uk/news/health-59418123
Covid: Trigger of rare blood clots with AstraZeneca jab found by scientists

Some people has different vaccines for second dose due to allergic reaction or to lack of availability. One couldn't 'choose' this as an option it was an exceptional circumstances thing.
There is a possibility that having a different vaccines broadens immunity.
I think that the specific clotting issue with AZ was less common with the second dose. I don't suppose a large number have had 3 doses to know as yet whether this trend has continued with the third.

I had Astra Zeneca for the first two doses, and Pfizer for the third. There was no option to have Astra Zeneca (I queried it) so unless there is a good reason for it, it's doubtful he will receive it for his third dose.

@CrunchyCarrot

*Sorry to Hijack bit how can someone who had AZ first dose get a Pfizer or moderna second dose ?

Vaccine centres all refuse saying second has to be same as first*

My DP got a Pfizer second dose after having AZ as his first. It wasn't because he had an adverse reaction to AZ, he just didn't want it after all the cases of blot clotting came out. He had a thorough discussion about it at the local walk-in centre who allowed him to have Pfizer as his second jab. So it is possible.

I guess need to keep trying different places then as so far they’ve all said they have to adhere strictly to the guidelines

@yikesanotherbooboo

Some people has different vaccines for second dose due to allergic reaction or to lack of availability. One couldn't 'choose' this as an option it was an exceptional circumstances thing. There is a possibility that having a different vaccines broadens immunity. I think that the specific clotting issue with AZ was less common with the second dose. I don't suppose a large number have had 3 doses to know as yet whether this trend has continued with the third.

We got told unless you were hospitalised after first AZ then they don’t class it as a reaction severe enough to warrant a diff second dose

I've not heard of anyone who had AZ for their first 2 having it as a booster. Only using moderna or Pfizer for boosters here despite having AZ twice before!

@dollywoodlooksgood

AZ has been authorised as a booster for those who cannot have the mRNA vaccines, I believe. I know I'm only one person, OP, but I've had 3x AZ and all fine.

@dollywoodlooksgood If I have a booster I only want the AstraZeneca one. How did you go about getting an AstraZeneca booster? Did your GP give it to you? What did you need to say to get it?

From looking at some Canadian data of side effects it looks the clotting issue is much rarer still with a second dose than first, so guessing that would apply to a third dose too. Astrazeneca have published some research on a group given three doses. Would have been a smallish group though so I doubt the clotting issue would have shown up.

That's helpful Grimbelina, thanks

I’m another person who’s had AZ for all three doses as my allergy history precludes the mRNA vaccine’s

I was quite unwell with my first jab, fine with my second and had an allergic reaction with the booster

@Tomnooktoldmeto

I’m another person who’s had AZ for all three doses as my allergy history precludes the mRNA vaccine’s

I was quite unwell with my first jab, fine with my second and had an allergic reaction with the booster

@Tomnooktoldmeto How did you go about getting AZ as a booster dose? Did you ask your GP? I only want AZ as a booster if I have to have one but none of the places near me offer it, only the mRNA vaccines which I don't want.

@soredust - you don’t have a personal choice about which to have as your booster. Pfizer/Moderna are being offered in almost all cases because clinical trials, which explored the different combinations of vaccine brands for the booster, found that the mRNA vaccines were the most effective as the booster.

The Green Book quote above shows that you’ll only get AZ if a health professional advises it, and that’s highly likely to be because there’s a compelling clinical need in your case, eg you had a severe allergic reaction to a previous Pfizer or Moderna dose.

You won’t be able to just find the right form of words and get it.

It would then also need to be specially arranged just for you, because most vaccination sites are doing Pfizer or Moderna.

Does anyone know if it's possible to find out in advance which booster is being given on a particular day? I don't want Moderna and I'd rather not waste my time and an appointment by turning up if I can't have Pfizer.

@PinkSparklyPussyCat - the NHS website where you can search for walk-ins lists the available vaccine(s): www.nhs.uk/conditions/coronavirus-covid-19/coronavirus-vaccination/find-a-walk-in-coronavirus-covid-19-vaccination-site/

Thank you @Wigeon. I can't believe how few walk in centres there are near me!

@PinkSparklyPussyCat

Does anyone know if it's possible to find out in advance which booster is being given on a particular day? I don't want Moderna and I'd rather not waste my time and an appointment by turning up if I can't have Pfizer.

For our local Boots it says on the government website when you search for it as a walk in. The centre I work at only has Pfizer, we have never had Moderna.