With no confirmation of how long the current Covid-19 vaccines provide immunity, and new vaccine escape variants circling, it’s looking likely that booster jabs will be needed later this year.

Initial studies suggest we will have protection for at least six months after vaccination with the Pfizer/BioNTech and Moderna vaccines. We could get to 12 months and find that protection lasts beyond that, but for now, because the vaccines have only been in use for a short time, we simply don’t know.

With that in mind, and worries over the Brazil and South Africa variants possibly evading the immune response from the existing vaccines on offer, vaccines minister Nadhim Zahawi has said priority groups could begin to get booster shots as early as September this year.

The shots would provide an immune system top-up while also offering some extra protection against new and more problematic variants doing the rounds.

The UK expects to have up to eight different vaccines in circulation by autumn. In the meantime, we asked the three current providers – Oxford/AstraZeneca, Pfizer/BioNTech and Moderna – where they’re at with a booster jab. 

Pfizer

The Pfizer/BioNTech vaccine is a mRNA vaccine. When injected, it introduces a messenger RNA (mRNA) sequence that tells your body how to fight the virus. It’s a bit like injecting an instruction manual into your body – this ‘manual’ contains the genetic instructions for the vaccinated person’s cells to produce the vaccine antigens and generate an immune response.

One of the perks of this type of vaccine is that the technology is pretty flexible in comparison to traditional vaccine technologies – so boosting can be done fairly easily, says Pfizer. “MRNA vaccines provide the ability to alter the RNA sequence in the vaccine to cover new strains of the virus,” explains a spokesperson. “If a strain that escapes protection from the vaccine were to emerge, the updated vaccine could be administered as a booster.”

Studies so far suggest that the Pfizer jab offers adequate protection against new circulating variants. One small study did suggest the percentage of positive antibodies that neutralised the South African variant was 10-fold lower for the Pfizer vaccine than against the original coronavirus strain, Web MD reports. 

However, the jab was found to work fine against the UK’s Kent variant (B.1.1.7 lineage). Another study concluded the jab worked well against the Brazil and Kent variants and had a robust but lower effectiveness against the South Africa variant. 

“While we have not seen any evidence that the circulating variants result in a loss of protection provided by our vaccine in our laboratory studies, we are taking multiple steps to be ready in case a strain becomes resistant to the vaccine,” says a company spokesperson.

Studies are currently underway evaluating the effectiveness of a booster shot of the existing Pfizer vaccine and also a new prototype vaccine based on the B.1.351 lineage, first identified in South Africa. 

AstraZeneca

The Oxford/AstraZeneca works slightly differently to mRNA vaccines – the vaccine is made from a weakened version of a common cold virus from chimpanzees. It’s also been tweaked so it contains genetic material shared by Covid-19. Once injected, it teaches the body to recognise Covid’s spike protein, so the immune system knows what to do if you come into contact with it. 

Because the vaccine is engineered in a lab, as the virus mutates, AstraZeneca says it can adapt the technology to keep pace with new variants, if needed.

There is some emerging evidence that the existing jab isn’t that effective against the South Africa variant. One trial implied as little as 10% efficacy, the Guardian reported.

A spokesperson tells HuffPost UK that, with the help of Oxford University, AstraZeneca has already started developing the next generation of Covid vaccines incorporating the genetic changes to the spike protein found in the new variants. “This can advance rapidly through clinical development so that it is ready for Q4 delivery [autumn/winter], should it be needed,” they added. 

Moderna

Like the Pfizer/BioNTech vaccine, the Moderna jab is a mRNA vaccine. Though Moderna didn’t respond to HuffPost UK’s request for an update on booster jabs, we do know that the company has been working on a new vaccine to target the South Africa variant.

It comes after a small study found the percentage of positive antibodies that neutralised the South African variant was 12-fold lower for the Moderna vaccine than against the original coronavirus.

Initial studies in mice have found the new and improve vaccines to target this variant produced antibodies to fight against it, the Times reported. 

Moderna is also working on a vaccine that combines the existing vaccine with the South Africa-specific vaccine. Pre-clinical trials of both these new vaccines in mice showed a boost in antibodies in the blood. Whether a booster will be ready for autumn remains to be seen.