The UK government said it would follow a new immunization strategy for the vaccine, which will prioritize giving the first in a series of two vaccine doses to as many people as possible, before administering a second dose up to 12 weeks later.
This will apply to both the newly approved Oxford/AstraZeneca vaccine and the Pfizer/BioNTech vaccine which is already being administered.
“This is important because it means that we can get the first dose into more people more quickly and they can get the protection the first dose gives you,” UK Health Secretary Matt Hancock told Sky News on Wednesday.
Hancock told the House of Commons that more than 21,000 people were currently in hospital with coronavirus in England. “Unfortunately this new variant is spreading across most of England,” he warned.
Some scientists have called on the government to impose even tougher restrictions to rein in the virus’ spread, such as delaying children’s return to in-person teaching in schools next year or imposing a full national lockdown.
Authorities declared a major incident Wednesday in the county of Essex, northeast of London, in response to “significant growing demand” on local hospitals after a surge in coronavirus cases there.
Dr. June Raine, chief executive of the Medicines and Healthcare products Regulatory Agency (MHRA) — the UK regulatory body — told a televised Downing Street briefing Wednesday that the newly approved Oxford/AstraZeneca vaccine could save “tens of thousands” of lives.
And she insisted that the public could have every confidence in its safety, effectiveness and quality.
“Our teams of scientists and clinicians have very carefully, methodically and rigorously reviewed all the data on safety, on effectiveness and on quality as soon as they have become available, and have done so around the clock, looking at all the tests and trials … no corners, whatsoever, have been cut,” she said.
Professor Wei Shen Lim, chair of the Joint Committee on Vaccination and Immunisation, told the briefing that “we can expect that the amount of vaccine available for use in the UK will substantially increase, very very soon. This increase in the vaccine supply will in turn allow a much higher rate of vaccine deployment across the UK, to all parts of the country.”
He added that the second vaccine dose was still important “because it may impact on the duration of protection.”
Both approved vaccines will be used across the UK, Lim said. “To facilitate rapid deployment within a mass vaccination program, and to avoid substantial vaccine wastage, it may be that in certain settings, one vaccine is offered in preference over another,” he said, adding that the deployment of both vaccines would allow for “rapid and high levels of vaccine uptake” across the country.
The Oxford/AstraZeneca vaccine can be kept at refrigerator temperatures of 2 to 8 degrees Celsius (36 to 46 degrees Fahrenheit) for at least six months.
Moderna’s vaccine has to be stored at minus 20 degrees Celsius (minus 4 degrees Fahrenheit) — or at refrigerator temperatures for up to 30 days — and the Pfizer/BioNTech vaccine has to be stored at minus 75 degrees Celsius (minus 103 degrees Fahrenheit), and used within five days once refrigerated at higher temperatures.
The vaccines are based on different technology. AstraZeneca’s offering — like Johnson & Johnson’s vaccine and Russia’s Sputnik V — uses an adenovirus to carry genetic fragments of coronavirus into the body.
Previously, the team developing the Oxford/AstraZeneca vaccine said it had an “an average efficacy of 70%,” with one dosing regimen showing an efficacy of 90%.
But the experts who gave Wednesday’s Downing Street briefing said a full analysis of the trial data had not borne out the team’s finding that that regimen — in which a half dose was followed by a full dose — was more effective. The MHRA approved the vaccine at two full doses, which has an efficacy of 62%.
Prof. Munir Pirmohamed, chair of the Commission on Human Medicines’ Expert Working Group, said the trial data had led scientists to recommend giving as many people as possible their first dose of vaccine with a second dose following within 12 weeks.
“Because of the design of the trial, some people got second doses at different time intervals. This allowed for an analysis of the effectiveness of the vaccine if you were to be able to delay between 4-12 weeks,” he said. “This showed that the effectiveness was high, up to 80% when there was a three month interval between first and second doses, which is the reason for our recommendation.”
Pirmohamed noted that partial immunity only kicked in 22 days after the first dose and urged people to continue to follow social distancing guidelines even once they have had their first jab.
UK government scientific adviser Professor Calum Semple welcomed what he called a new, “sophisticated approach,” telling Sky News that a “one-dose approach to start with will protect a great many people.” According to Semple, evidence from vaccine trials has shown that a single dose has not only prevented people from getting severe disease, but also has prompted a “very good immune response” in frail and elderly people.
However, some scientists called for greater clarity over the data underpinning the latest vaccine approval and the country’s new immunization strategy.
Dr. Jonathan Stoye, of the Francis Crick Institute, told the UK’s Science Media Centre that important questions remained unanswered, including the real efficacy of the vaccine, how well it worked in older people and whether it prevented transmission between people.
“It remains unclear exactly how much protection is offered, and the regulators are using unpublished data to come to their judgment,” said Dr. Simon Clarke, Associate Professor in Cellular Microbiology at the University of Reading.
“When questioned, the regulators floated an efficacy of 70% between 22 days and 12 weeks, but it seems likely that this is a fleeting maximum rather than a consistent level of protection. The vaccine’s efficacy after two doses is 62%, so it looks likely that the higher number would only be very short-lived.
“At a time of increasing rates of infection, hospitalization and death from Covid-19, greater clarity is urgently needed over any risks associated with extending the second dose window to 12 weeks.”
The UK also updated its advice on administration of the Pfizer/BioNTech vaccine Wednesday.
It now recommends an interval of at least 21 days between the first and second dose, rather than requiring the second dose to be 21 days after the first.
The vaccine can now be considered for use in pregnancy when the potential benefits outweigh the risks, following an individual discussion with every woman, Raine said. Woman who are breastfeeding can now also be given the vaccine, subject to that individual discussion.
The vaccine can also now be given to people with allergies, provided they are not allergic to any of the ingredients in the vaccine, she said.