The head of AstraZeneca has said Europe's continuing coronavirus crisis may be linked to countries choosing the wrong vaccine for their elderly populations.
Hospitals on the continent are dealing with an influx of new patients and a surge of new cases, sparking fresh lockdowns and restrictions in countries such as Austria and the Netherlands.
Pascal Soriot, the chief executive of the Cambridge-based drug maker, said he believes this may be the result of waning antibody responses, particularly in vaccines that use mRNA technology.
Following its approval, the Oxford-AstraZeneca vaccine was used to inoculate older people in Britain, but concerns over possible blood clot side-effects saw its use curtailed in much of the EU.
“When you look at the UK, there was a big peak of infections, but not so many hospitalisations relative to Europe”, he told the BBC's Today programme.
“In the UK, this vaccine was used to vaccinate older people. Whereas in Europe, initially, people thought the vaccine doesn't work in older people.”
Mr Soriot said vaccines which use mRNA technology, such as Moderna and Pfizer/BioNTech, initially generate a large antibody response, but that protection begins to decrease shortly afterwards.
By contrast, vaccines which use viral vectors, such as the Oxford-AstraZeneca vaccine, may create a strong T-cell response, which he said the “body remembers longer".
Studies show that the AstraZeneca vaccine, marketed under the Vaxzevria brand name, stimulates T-cells to a higher degree in older people, he said.
“So you see everybody's focused on antibodies, but you see them decline all time. What remains very important is the T-cell response.
“And as soon as the virus attacks you, they wake up and they come to the rescue and they defend you.
“But it takes them a little while. So you may be infected. But then they come to the rescue and you don't get hospitalised.”
Asked whether that is because of the AstraZeneca vaccine being used among older people, he added: “There’s no proof of anything, we don’t know, but we need more data to analyse this and get the answer.”
Earlier this year, the EU launched legal action against AstraZeneca over shipment delays of 200 million vaccines which threatened to derail the bloc's initial inoculation efforts.
AstraZeneca said the legal action was “without merit” before the parties agreed to the delivery of the pending vaccines in 2022.
The resulting row led to Brussels refusing to renew a contract for vaccines in June, and instead opting to buy nearly two billion doses of the Pfizer/BioNTech drug.
The WHO said Europe remains “in the firm grip” of the coronavirus pandemic, with reported daily deaths rising to almost 4,200 a day — double the number of deaths a day at the end of September.
Reported deaths from the virus have already passed the 1.5 million mark for the 53 countries that make up the WHO European region, the global health agency said.
The Netherlands on Tuesday started transporting some of its Covid-19 patients across the border to Germany to ease pressure on its hospitals.
German hospitals in total have offered 20 beds for patients from the Netherlands, after treating dozens during previous waves of the pandemic.
European countries are now racing to deliver booster shots to older and more vulnerable patients, to help stem the number of deaths as winter approaches.
However, British health authorities have not chosen to use the AstraZeneca vaccine for their booster programme, which is now being rolled out to people aged over 40.
Mr Soriot said the decision made sense as it is simpler to use one vaccine, as opposed to different vaccines.
“What is not used here is used elsewhere in the world. Different countries will make different decisions based on their circumstances”, he said.
AstraZeneca had initially decided to make its vaccine non-profit, but has revealed it will now increase pricing for developed nations while keeping costs low for poorer countries.
“But you know, we will of course adapt to every circumstance and countries that have low purchasing power will be supplied at no profit or very low price and others will be a bit more”, Mr Soriot told Sky News.
It comes as Prince Charles is set to open a new AstraZeneca research centre in Cambridge.
The £1 billion ($1.34bn) Discovery Centre, which will accommodate more than 2,200 research scientists, is located in the Cambridge Biomedical Campus.
Mr Soriot said the location of the site will make it a “fantastic place” to research new medicines.