The UK government has said it wants to give a single dose of Covid vaccine to as many members of priority groups as possible.
While everyone should get a second dose within 12 weeks, this is a lot longer than the gap of three weeks between doses that was originally planned.
The World Health Organization’s expert scientific advisors have said they do not recommend that other countries follow the British approach – but the WHO also says it understands why the UK has chosen to go down this road.
There are big differences of opinion among experts around the world about whether the British approach is the right one. Here’s what we know about the UK’s vaccination strategy.
How is the British approach different?
Early in December last year, Britain become the first country in the world to begin vaccinating citizens in large numbers using a vaccine tested and signed off by a national regulator.
The first people who received the vaccination – made by Pfizer and BioNTech – were told to come back in three weeks for a second “booster” injection.
The Oxford/AstraZeneca vaccine was also approved by the regulator soon after.
But a week ago, the independent experts who sit on the UK’s Joint Committee on Vaccination and Immunisation (JCVI) gave the government radically different advice.
The JCVI said: “Given data indicating high efficacy from the first dose of both Pfizer-BioNTech and AstraZeneca vaccines, the committee advises that delivery of the first dose to as many eligible individuals as possible should be initially prioritised over delivery of a second vaccine dose. This should maximise the short-term impact of the programme.
“The second dose of the Pfizer-BioNTech vaccine may be given between three to 12 weeks following the first dose. The second dose of the AstraZeneca vaccine may be given between four to 12 weeks following the first dose.”
The four UK chief medical officers have agreed to follow the JCVI advice.
Why are we doing this?
The scientists who advice the government believe the benefit of vaccinating more people outweighs the risk of individuals not having as strong a protection against infection as they might have with two doses.
This is in the context of rapidly rising numbers of coronavirus infections and deaths across the UK and warnings that the NHS may struggle to cope with caseloads soon.
On Tuesday Professor Chris Whitty, chief medical officer for England, said: “In net public health terms there will be substantially more protection by going faster, not with the absolutely complete protection – we fully agree we need a second dose for everybody – but with the great majority of the protection for that initial period so we get twice as many people vaccinated.”
It was clear from Professor Whitty’s remarks that availability of vaccines is an issue. As FactCheck has reported before, far fewer doses of the Pfizer BioNTech and Oxford/AstraZeneca vaccines are available for use now than ministers first expected.
The UK government said last year that it hoped to have 30 million doses of Oxford/AstraZeneca vaccine ready by September. In fact, only around half a million doses were ready for use by New Year’s Day.
Professor Whitty said: “Clearly if we had infinite vaccine, we might have taken different approaches, but we don’t.
“At this point in time, for the next three to four months the number of vaccines we have available is going to constrain our ability to get through the 25 to 30 million people we must do to get through (the groups prioritized by the JCVI).”
What is the scientific evidence?
The UK authorities accept that they are acting in the absence of complete data here. There is limited evidence from clinical trials that the vaccines will continue to offer protection 12 weeks after the first dose.
The Pfizer vaccine was only tested with a three-week delay between doses, and the company has said: “There is no data to demonstrate that protection after the first dose is sustained after 21 days.”
The Oxford/AstraZeneca situation is slightly different. The researchers said most people who took part in clinical trials in the UK got their booster dose more than 12 weeks after the first one and there was little difference in protection between those participants and people who got the second jab earlier.
The UK authorities believe one dose of either vaccine will still offer significant protection in the short term – around 90 per cent efficacy for Pfizer/BioNTech and 70 per cent for Oxford/AstraZeneca.
What does the WHO say?
The WHO’s SAGE advisory committee (not to be confused with the British body of the same name) says the lack of clinical data means it cannot recommend that other countries follow the UK approach.
This has been slightly misreported today as the WHO criticising Britain or issuing a warning not to proceed with the strategy. In fact, WHO SAGE’s remarks are quite nuanced.
Dr Alejandro Cravioto said the panel recommended giving a second dose of Pfizer vaccine at three to four weeks, but added: “SAGE made a provision for countries in exceptional circumstances of vaccine supply constraints and epidemiologic settings to delay the administration of the second dose for a few weeks in order to maximize the number of individuals benefiting from a first dose.”
He added: “I think we have to be a bit open to these types of decision that countries need to make according to their own epidemiological situation.
“A country might need to use the vaccine in a different way for many different reasons and that is something that competes then to a local decision which goes beyond the recommendations that we’re able to make at this time.”
What do other scientists say?
As so often in this pandemic, it’s complicated and there is no expert consensus: it’s possible to find outspoken critics of the British approach, while other scientists back the UK strategy.
America’s vaccine regulator, the Food and Drug Administration, said plans to use vaccines with untested dosing schedules were “premature” and “concerning”.
An Israeli epidemiologist called the British move “an act of desperation”.
But independent scientific groups like the Royal College of General Practitioners and the British Society for Immunology (BSI) backed the UK approach.
The BSI said in a statement: “Most immunologists would agree that delaying a second ‘booster’ dose of a protein antigen vaccine (such as the two approved COVID-19 vaccines) by eight weeks would be unlikely to have a negative effect on the overall immune response post-boost.
“We also would not expect any specific safety issues to arise for the individual due to delaying the second dose, other than an increased potential risk of disease during the extended period due to lowered protection.”
Some independent scientists who comment on the Covid-19 pandemic via the Science Media Centre have also said that they do not expect a delayed second dose to substantially affect overall levels of protection for a vaccinated individual.
Prof Stephen Evans, Professor of Pharmacoepidemiology, London School of Hygiene & Tropical Medicine, said: “We have some evidence that the efficacy is quite good, and there are no reasons to believe it will show a sudden decline between three and twelve weeks.
“We must take into account that in the current UK context there will be many more cases of disease and therefore more deaths by vaccinating fewer people.”
He added: “This is not a simple problem. The idea that there is a definite clear-cut answer is not true because respected scientists differ in their views.”