With the emergence of the Omicron variant, the Covid booster vaccination programme is being ramped up.

All adults over the age of 18 are to be offered the top up by the end of January 2022, the Government has said.

Hospitals, vaccination centres and 1,500 community pharmacies will be offering us the jab but it won’t be Oxford’s AstraZeneca vaccine.

This is why you won't be given it and what this means if you had AstraZeneca for your original two doses.

Why is AstraZeneca not being used as a Covid booster?

AstraZeneca was developed at the University of Oxford in partnership with the Anglo-Swedish pharmaceutical company of the same name.

It was one of the three vaccines - including Pfizer/ BioNTech and Moderna - that we have been offered as part of the UK's vaccination programme.

However, AstraZeneca works a little differently from the other two since it is now what the Joint Committee on Vaccine and Immunisation (JCVI) class as a messenger RNA (mRNA) vaccine.

The mRNA vaccines help our bodies reproduce the SARS COV-2 protein and then break it down through direct immune response.

The JCVI looked at various combinations of the Covid vaccines in circulation and analysed their effectiveness as boosters.

READ MORE: NHS Omicron PCR test scam email: What it looks like, how to avoid it

READ MORE: 'Covid tests and 7 days quarantine or fines' on Christmas flights to US from UK

"JCVI advises a preference for the Pfizer-BioNTech (BNT162b2/ Comirnaty) vaccine to be offered as the third booster dose irrespective of which product was used in the primary schedule," the JCVI confirmed in a statement in September.

"There is good evidence that the Pfizer-BioNTech (BNT162b2/ Comirnaty) vaccine is well tolerated as a third dose and will provide a strong booster response."

From this evidence, the JCVI recommends that both Pfizer/ BioNTech and Moderna had "a strong booster response" and that they should be prioritised in the booster rollout.

JCVI has said that Pfizer is the preferred booster regardless of what vaccine you have received already.

What is different about AstraZeneca?

Just like the other vaccines, AstraZeneca works by telling the body to build spike proteins and build an immune response by breaking them down. 

But AstraZeneca does this by using double-stranded DNA rather than single-stranded RNA like Pfizer/BioNTech and Moderna.

AstraZeneca is a useful vaccine since DNA is not as fragile as RNA and the vaccine doesn't need to stay frozen and has a 63% efficacy against symptomatic Covid, according to the World Health Organisation.

In contrast, the New England Journal of Medicine found Moderna had a 93.6% level of effectiveness and 88% for Pfizer.

When would I get the AstraZeneca vaccine?

There are still some cases that you may still receive the AstraZeneca vaccine as a booster.

AstraZeneca would be made available to you if:

  • you are allergic to any of the ingredients in Pfizer/ BioNTech or any other mRNA vaccine.
  • you previously received the two AstraZeneca doses originally.