UK orders 60m extra doses of Pfizer vaccine for autumn ‘boosters’

The UK has purchased 60m extra doses of the BioNTech/Pfizer vaccine in preparation for a “booster” campaign for the most vulnerable in the autumn.

Interest in delivering booster shots later in the year has been exacerbated by rising numbers of concerning new variants in the UK, at least one of which has shown some signs of being able to evade immunity conferred by vaccines and prior infection.

“Our vaccination programme is bringing back our freedom, but the biggest risk to that progress is the risk posed by a new variant,” said Matt Hancock, health and social care secretary. “We’re working on our plans for booster shots, which are the best way to keep us safe and free while we get this disease under control across the whole world.”

News of the new Pfizer dose purchases, which takes the total procured to date to 100m, came after Dr Mary Ramsay, head of immunisation at Public Health England, told MPs on Wednesday of evidence suggesting that immunity to Covid-19 wanes at a slower rate after vaccination than had previously been thought.

This, Ramsay said, suggested that some annual booster shots could be delayed and others may not be needed at all.

“We think and we assume and we will be able to show, I hope, that those will extend protection for several months if not potentially years. It will be difficult to decide when the best time to boost is but there’s no point boosting if you’re already protected,” she said.

Early modelling of the duration of immunity after vaccination was based on the influenza jab, which does not offer such high levels of protection and does have to be topped up every year, Ramsay added.

“If a new variant comes in and our current vaccine isn’t working, that will be our biggest pressure to boost,” she said.

Earlier this month Pfizer announced that antibodies elicited by its jab persist for at least six months, even against some of the more concerning variants. Another study, conducted by researchers in the US, found that immunity provided by the Moderna vaccine lasted for a similar period.

While there is limited data beyond that time period — because the vaccines have only been in widespread use for five months — most experts believe the jabs are likely to confer protection for substantially longer.

T-cells, which can “remember” past infections and kill pathogens if they reappear, are thought to have a big influence on how long people remain resistant to infection and disease. Some scientists think they could provide at least some protection for up to two years after infection with Covid-19.

The UK government said it will publish further details on its autumn booster programme for the most vulnerable “in due course” and the final policy will be informed by advice from the Joint Committee on Vaccination and Immunisation (JCVI) as well as results from clinical trials studying the use of different combinations of approved Covid-19 vaccines.

Ramsay, who was answering questions from parliament’s science and technology select committee, said vaccines were likely to save more than 70,000 lives in the UK. Modelling suggests they have already prevented at least 10,400 deaths.

The risk of suffering a rare blood-clotting reaction after receiving the AstraZeneca vaccine is about 1 in 100,000, Sir Munir Pirmohamed, chair of the Commission on Human Medicines, which has been advising the UK government on the safety of vaccines, told the committee.

He added that the only risk factor for blood clotting identified to date was age, with young people showing a “higher risk” of the rare side effect, which is lethal in about a fifth of cases.

He noted, however, that in India only two cases of the blood clots coupled with low platelets had been identified after 100m doses of the AstraZeneca vaccine had been administered, suggesting a genetic risk factor may also be at play.

Work is ongoing to test whether giving a reduced dose of the AstraZeneca vaccine would cut the chance of the clotting reaction, Pirmohamed added.

“As a pharmacologist, I firmly believe in a ‘dose response curve’, so it is important to look at that,” he said. “Further work is being undertaken to understand the dose response relationship in terms of efficacy and safety with that vaccine.”