Boosters and Third Doses - is there a differ... - Vasculitis UK

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Boosters and Third Doses - is there a difference?

MAC12 profile image

I have GPA and recently had what was called a 'booster' dose following the two Covid vaccinations I received earlier in the year. Since receiving the booster, I have had a letter from the NHS stating that I may also need a third dose. However yesterday I had one of my twice-yearly consultations with my consultant who told me there is in fact no difference between a third dose and a booster dose. This conflicts with information in the latest VUK magazine which states that a 'booster dose is half a normal dose'. Can anyone clear up this confusion?

16 Replies
vivdunstan profile image

There can be a difference if the 3rd vaccine given is Moderna. Only 1/2 a full dose is given for the Moderna booster, versus a full Moderna dose for the 3rd primary vaccine for severely immunosuppressed people. There is no difference in dose if Pfizer was given. Can you remember what vaccine you received?

However the way the doses are recorded in the computer system _is_ different. It is likely that those who receive a 3rd primary vaccine now will receive a booster as well as 6 months time. Whereas those who get a booster now won't. It is very important that those who should be getting a 4th vaccine are recorded correctly in the computer system. This may cause problems for you getting a 4th vaccine, unless you can get that computer record for your 3rd vaccine changed from booster to 3rd primary vaccine. Note 4th vaccines are not confirmed yet, but are looking likely. But only for the severely immunosuppressed, i.e. those who get 3rd primary vaccines now not boosters.

The difference is purely eligibility: if you were judged to be immunosuppressed at the time of the first two jabs then you qualify for a third primary dose to complete the course. THEN you get a booster as a 4th jab. The third primary jab can be given any time after 8 weeks post the second jab, you don't have to wait the full 6 months that precedes the booster. The third primary doses are being allocated by the GPI think and you get a call for them.

I can't speak for the Moderna half dose - that was a suggestion at one point but whether it was adopted I don't know. But otherwise the doses used for the 3rd primary and the boosters are the same. How it is recorded is important though.

MAC12 profile image
MAC12 in reply to PMRpro

Thanks. So basically, as my consultant told me, there is no difference between normal dose and booster shot? It’s incorrect that the booster is a half dose?

MAC12 profile image
MAC12 in reply to MAC12

I received 2 Astra Zeneca initially and ‘booster’ was Pfizer.

PMRpro profile image
PMRpro in reply to MAC12

Certainly in your case - a full dose of Pfizer was to be used as the 3rd primary if the first 2 had been AZ.

PaddyPop profile image
PaddyPop in reply to MAC12

If you meet the criteria laid down by the JCVI then you will be given a third dose and possibly a booster in 6 mths. If you do not meet the criteria you will be given a booster. The third dose and the booster will be the same but if then given a booster in 6 mths and the booster is Pfizer you will be given another full dose but if it’s Moderna it may be half a dose.

MAC12 profile image
MAC12 in reply to PMRpro

What is the reason that the way 3rd primary/ booster is recorded is important? Is it because the booster does not appear on your Covid pass which could cause problems if required to present it - eg when travelling? My 'booster' dose which I now understand is the same as a 3rd normal dose can be seen on my NHS App vaccination record where it states 'Immunisation course to maintain protection against SARS-Cov-2. However it does not yet appear on my NHS Covid pass. I called my GP surgery to ask why and they did not have an answer. Any ideas anyone??

PMRpro profile image
PMRpro in reply to MAC12

Because that entitles you to a booster in 6 months time - having a jab labeled booster now may not get that booster in 6 months. The third primary is (probably) required to get your immune response up to the same level as that achieved after 2 jabs by normal/healthy people.

Many thanks. I know a number of people with compromised immune systems who are anxious because of the confusion over this. They are worried they've had a 'booster' and are now being informed they should have had a third normal dose. If the two things are the same in many cases then they should not be worrying.

Hi, I’m severely immunocompromised and also was anxious but at my recent appointment the consultant not only confirmed it’s a full dosage but told me I’m already in system for March 4th jab. So it’s just the language which is different, not the dosage.

No difference except if you have Moderna. However, as vivdunstan says it’s how it’s recorded that will/could make a difference. Sadly, I’ve been unsuccessful so far in persuading my GP practice to change mine to being recorded as a third dose, not a booster. They insist it makes no difference, also have commented that once I’m eligible for the booster in 6 months time, they won’t be doing covid vaccinations any more, said it’s all moving to mass vaccination centres. They don’t really want to know…. I’ll keep on trying, though!

If you got Pfizer there is no difference - its a full dose for everyone. If you got Moderna then you only got a half dose so you need to do something about that.

Hi MAC12, I have just had my fourth dose! Yes. It’s a mess out there. I had my letter for the third dose as I was on high dose of Prednisolone for my first two. I got an appointment at a vaccination centre. First they wanted me to have a third Astrozeneca which I questioned because JCVI said a third different vaccine is more effective. So they gave me Moderna. A week later I got a phone call from the nurse in charge saying I should have been given a full dose so I needed to return for the other half. I do so hope I get some antibodies this time. I had none with the first two. I have been unable to find any info on the dose of Moderna for third dose.


I recently got called for my third jab and after driving through the vaccination centre I checked the card from the nurse which said booster.

I called the surgery later that day and spoke to the COVID nurse who informed me not to worry and there was no difference between the third jab and the booster.

The only thing they need to ensure is they complete the records to say I was due a booster in 6 months time.

There has been so many conflicting stories about this. My third jab was from Pfizer.

MAC12 profile image
MAC12 in reply to Peddy1968

Thanks for this and the other replies. It seems to me then that, in most (though not all) cases, there is actually no difference between the 'booster' and 'third dose'. This has caused a lot of unnecessary anxiety and confusion.

MAC12 profile image
MAC12 in reply to MAC12

Basically, as far as I can see, the situation is one of massive confusion!

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