Preparations are being made in the UK for a potential third dose of Covid vaccines to ward against the virus over the winter months and any new variants.
The rollout could be as soon as September, with the most vulnerable once again prioritised.
But how would this work and do we really need a booster jab? Here's what we know.
1) Will we have a booster jab in the Autumn?
The short answer is that this hasn’t been decided yet, but preparations are being made to be ready for another rollout from as early as September.
The Joint Committee on Vaccination and Immunisation (JCVI) has outlined interim advice for a potential booster programme – but whether or not the government goes ahead with it depends on data and final consultations over the coming weeks.
This is what a spokesperson for the Department of Health and Social Care said: “The booster programme – which would ensure millions of people most vulnerable to Covid-19 will have the protection they have from first and second doses maintained ahead of the winter and against new variants – will be informed by the JCVI’s final advice.
“We are working with the NHS as they draw up detailed plans to deliver this booster vaccination programme, alongside the annual flu vaccination programme, and more details about rollout will be set out in due course.”
2) Do we need a third jab?
Part of the reason a third jab is being considered is that social restrictions are expected to remain relaxed to close to pre-pandemic norms this winter, which means Covid could circulate through the population alongside other viruses, like the flu.
So this vaccine booster, if it runs, would be done alongside the annual flu jab.
The JCVI states in its advice: “The timing and magnitude of potential influenza and SARS-CoV2 (Covid-19) infection waves for winter 2021 to 2022 are currently unknown.”
But this doesn’t mean a third dose is an inevitability. The JCVI also lists certain factors they need to consider before offering final advice to the government.
These include data from clinical trials, real-world effectiveness and on the strength of protection vaccines maintain beyond six months.
Israel, France, Germany and many Middle Eastern countries have already started administering booster jabs – but there are growing calls to prioritise doses for the rest of the world.
Professor Danny Altmann, an immunologist at Imperial College London, told ITV News there is a global health debate around this question.
He said: “Are our precious vaccine doses better used for giving a third dose to people who've already had two, or getting a first and second dose to people in the world who’ve had none, who are in countries where the next variant is going to come from?”
3) Can we mix vaccines for the booster? Pfizer after two AstraZeneca jabs, for example?
A study by Oxford University’s Com-Cov group, which compares vaccine combinations, suggested mixing jabs still offers good protection against the virus.
The study, published at the end of June, found that using Pfizer followed by Oxford or vice versa induced high concentrations of antibodies against the spike protein of the virus when doses were given four weeks apart.
It also suggests people who have had two Oxford jabs could have more antibodies if they were given a different booster.
More antibodies do not necessarily mean more protection against the virus.
The findings could allow flexibility in the UK and global vaccine rollouts, allowing people to receive whatever jab is available, rather than waiting for a matching one.
Reacting to the report, deputy chief medical officer Professor Jonathan Van-Tam said it is unlikely the current approach of sticking the same vaccine given will change.
“Given the UK’s stable supply position there is no reason to change vaccine schedules at this moment in time,” he said.
4) Do we have the infrastructure to administer millions of boosters?
The largely successful rollout for the first two doses relied on thousands of volunteers, NHS staff and logistical organisation to quickly vaccinate the most vulnerable to Covid-19 in the UK.
Vaccine supplies should remain steady, with the UK long-since securing orders from a variety of manufacturers – including 30 million from the single-dose solution made by Janssen, which is owned by Johnson & Johnson – for later in 2021.
Another reason why the JCVI have published interim advice is so preparations can be made in case a similar scale of infrastructure is needed once again.
Professor Altmann said: “It was absolutely heroic and stellar to get it done and get it done as well as it was done for doses one and two.
“And if you've done it for doses one and two, maybe it would be even more doable for dose three.”
But the real question, he argues, is if it is vital to administer a third dose.
“How do we know if it's vital? What's the data and who's it vital for?”
The JCVI’s interim advice is that a booster jab should be offered to groups in two stages, with the following prioritised for an appointment as soon as possible from September as part of stage one:
adults aged 16 and over who are immunosuppressed
care home residents
all adults aged 70 or over
adults aged 16 and over who are considered clinically extremely vulnerable
frontline health and social care workers.
In stage two, the following would be targeted:
all adults aged 50 and over
all adults aged 16 to 49 years who are in an influenza or Covid-19 at-risk group
adult household contacts of immunosuppressed individuals
5) How long will we need boosters for?
The flu jab runs annually, but that doesn’t mean a Covid booster will follow suit.
As Professor Altmann explains: “The reason we have flu top ups every year is not because there's something wrong with our immune response to flu.
“It's because it's a carefully variable family of viruses, where you never know which version is going to come back the following year.
“Coronaviruses aren't like that. We have a slightly different problem with the variants of concern, so a top-up would really be predicated on the idea that people's immunity is waning very fast and they're not protected anymore.
“In most people that we look at, we don't see that situation. We think they're probably good for quite a while to come.”
He added that data around the most vulnerable must be monitored and then a decision must be made on whether certain groups will need another jab or not.
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