Covid vaccine booster: when could top-up jabs be rolled out and will vaccines be mixed?

More than 36 million people have now received two doses of a Covid vaccine, with more than 46 million people having received their first dose.

As the vaccination programme progresses, plans are in place to begin vaccinating people with Covid boosters during the autumn and winter months.

But how could this work and will vaccines be mixed?

Here’s what you need to know.

When will the Covid booster vaccination programme start?

At the moment, it looks likely that the UK will roll out Covid vaccine boosters in the autumn, says Dr Jonas Nilsen, co-founder of vaccination specialists, Practio.

Dr Nilsen said this is “in order to ensure protection for the most vulnerable groups through the winter.”

He also noted that the Joint Committee on Vaccination and Immunisation (JCVI) has recommended that certain groups are prioritised for the booster jabs, including people who are immune-compromised, those who live in care homes, and frontline health and social care workers.

NHS England said that the JCVI “advises that any potential booster programme should begin in September 2021, in order to maximise protection in those who are most vulnerable to serious Covid-19 ahead of the winter months.”

Martin Michaelis, Professor of Molecular Medicine at the University of Kent, explains that vaccine boosters are currently planned for everyone who is 50 years of age or older, probably in combination with a flu jab.

He says that “there is concern that the protection provided by the first two Covid-19 vaccinations weakens over time” and a booster vaccination is therefore “expected to prevent this or even to result in a further increased protection level.”

Dr Nilsen notes that the vaccine rollout during the autumn is expected to take place with the help of community pharmacies, which will then lighten the load for GP surgeries that are “already stretched for services.”

He also explains that in the future, Covid-19 booster vaccines will probably be administered in the same way as the flu jabs are at the moment.

Will vaccines be mixed when it comes to giving boosters?

Many people may be wondering if the booster vaccine they receive will be the same as the doses they have previously received, with Pfizer, Moderna and AstraZeneca all currently being administered in the UK.

Dr Nilsen says that although preliminary data suggests that mixing vaccine doses provides robust protection against Covid, there is not yet “a consensus on whether mixing vaccines is more beneficial in providing wider protection against the virus across the country’s population.”

He said that as of yet, there are no plans to mix vaccine doses, “particularly since the current vaccination programme has been so effective."

Prof Michaelis further builds on this, as he says “there is a growing body of evidence showing that the mixing of different Covid-19 vaccines also results in effective protection from Covid-19.”

He explains that this is “actually not surprising,” as it is a common strategy to combine different vaccine types to achieve a better immune response in the development of vaccines, for example for diseases such as the Ebola virus.

The booster vaccine may therefore differ from the one that someone initially received, he notes.

However, Prof Michaelis explains that this will depend on the data that will become available between now and the rollout of the booster vaccinations.

He says that although there is currently sufficient data showing that using a different vaccine should not be a concern, further research could show that using a different vaccine actually provides a higher protection than using the same one again, and therefore “mixing vaccines may become the new strategy.”

“There is always the possibility that new Covid-19 variants emerge and that the vaccines need to be adapted to cover these new strains,” he adds.