As the centrepiece of the UK’s strategy to curb Covid this winter, the UK’s booster vaccine rollout is gathering pace.
By the end of October nearly eight million third jabs had been administered across the country – but criticism of a slow vaccination drive is mounting amid concerns that millions of vulnerable people remain at risk.
Here, we take a look at who is eligible for booster shots, how to get one and whether vaccines can be “mixed and matched”.
Who is eligible for a booster?
The NHS is offering booster shots to priority groups deemed most at risk of Covid-19 and who received their second vaccine at least six months ago – although plans are already underway to reduce this to five months.
Currently the nine groups outlined by the Joint Committee on Vaccination and Immunisation (JCVI) include those aged 50 and over, frontline healthcare workers and people living or working in care homes.
Individuals aged 16 and over with an underlying health condition that puts them at high risk of Covid-19, or who live with or care for someone who is more vulnerable to the disease, are also eligible.
How do you get a shot?
Anyone in these nine priority groups can access a booster vaccine six months after their second dose.
It is possible to book a shot online or by calling 119. The NHS may get in touch with you directly, however the Government is urging people to book a slot themselves as not everyone who is eligible has been contacted.
From November 1 anyone who is eligible for a booster can get one by going to an NHS walk-in centre, in a bid to boost uptake before the winter.
Dr Nikki Kanani, a working GP and also deputy lead for the NHS Covid-19 vaccination programme, said: "The booster is not just nice to have, it is really important protection ahead of what we know will be a challenging winter."
When does immunity from the first two vaccine doses start to wane?
Mounting evidence suggests that protection begins to fall within around six months of the initial two doses.
Data based on the Zoe Covid Study app has suggested protection against infection after two shots of Oxford-AstraZeneca drops from 77 per cent after one month to 67 per cent after five to six. For Pfizer, this fell from 88 to 74 per cent.
More recent analysis published in the Lancet suggests that, while two doses of Pfizer are 90 per cent effective against hospitalisation for at least six months, they are only 47 per cent effective against infection after that period.
Meanwhile, research from Imperial College’s React study has shown breakthrough infections become more common as time elapses.
Overall, the study concluded that infection rates were three to four times higher among unvaccinated people, compared to those who had been given two shots. But while rates in fully vaccinated people stood at around 0.35 per cent in the three months after their second dose, this rose to 0.55 per cent among those double jabbed three to six months previously.
Experts say these studies, combined with similar research from countries such as Israel, paint an increasingly clear picture of waning immunity after five to six months – especially in those with weaker immune systems.
However, the European Centre for Disease Prevention and Control (ECDC) said all the vaccines used in Europe provide a high level of protection against serious illness, hospitalisation and death: the main objectives of countries’ vaccination strategies.
This suggests there is “no urgent need for the administration of additional doses of vaccines to fully vaccinated individuals in the general population”, the centre said.
Do you need a booster if you’ve had Covid?
The NHS is offering all those eligible a booster jab, regardless of whether they have had a previous infection. However, you must have the jab at least 28 days after testing positive for the virus.
Data from the Zoe app looking at people who were infected with Covid before being vaccinated, however, did show that their immunity against the virus was higher than through infection or vaccination alone.
Researchers found that two doses of the AstraZeneca vaccine gave 71 per cent protection against infection, increasing to 90 per cent for people who had previously tested positive for Covid-19.
Meanwhile two doses of the Pfizer vaccine provided 87 per cent protection, which went up to 95 per cent for people who had already been infected with the virus.
Which vaccines are on offer?
Most people in the UK will be offered either the Pfizer or Moderna vaccine, regardless of which vaccine they initially received, according to NHS England.
Only those who cannot have the mRNA vaccines because they are allergic or immunocompromised will be offered AstraZeneca, the JCVI has said.
Is it safe to mix and match different Covid vaccines?
While there haven’t been many studies on mixing different vaccines most evidence suggests that it is safe. Data from Oxford University's Com-Cov study, which is looking at mixing first and second doses of vaccines, has shown no safety concerns so far, although researchers note the numbers are small.
Studies have also shown that mixing the first and second dose are a potent immunity booster – and is more effective than two doses of the same vaccine.
Can you have the booster shot alongside the flu jab?
Yes. Most people who can have a coronavirus booster shot are also eligible for their flu jab and the NHS says it is safe to have them both at the same time.
Are other countries also rolling out booster jabs?
Much of the rich world is rolling out boosters. Policies vary slightly according to who is eligible and which shots are used, but in general the approach is relatively similar to the UK’s.
By contrast the majority of people in many lower income countries have struggled to access even one Covid shot - less than three per cent of all vaccines administered worldwide have been in Africa, for instance.
Agencies including the World Health Organization and Gavi, the Vaccine Alliance have warned that leaving vast swathes of the world unvaccinated could prolong the pandemic and accelerate the emergence of new variants.
They have called for booster rollouts to be paused – except for those who had China’s Sinopharm or Sinovac vaccine or are immunocompromised – until imbalances in the global rollout are redressed.
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