Pascal Soriot told BBC Radio 4’s Today programme that heightened T-cell immunity could be giving those who received the Oxford/AstraZeneca jab more durable immune protection against the virus.
His comments came as the former chair of the UK vaccine taskforce Dame Kate Bingham urged the government to do better in its preparation for future disease outbreaks. Writing in the Times, she said that the machinery of Whitehall was “dominated by process, rather than outcome, causing delay and inertia”, adding that the jab rollout would have been delayed if it had been left to the normal workings of government.
Germany was the first European country to recommend not giving the AstraZeneca jab to those aged over 65 in late January, citing a lack of efficacy data for the vaccine in this age group. Other European countries swiftly followed with similar recommendations, including Italy, France, Poland and Sweden, although many later reversed this guidance following the publication of further efficacy data.
Some eventually even said it should only be used in older age groups, after the the European Medicines Agency (EMA) reported a possible link between the vaccine and very rare cases of blood clots. Possibly as a result of these mixed messages, many Europeans were initially reluctant to receive the jab.
Soriot was careful not to apportion blame, but said the high uptake of the vaccine among elderly people during the UK’s initial vaccine rollout might help to explain why hospital admissions in the UK have remained relatively low despite continued high levels of infection.
He said: “It’s really interesting when you look at the UK. There was a big peak of infections but not so many hospitalisations relative to Europe. In the UK [the Oxford/AstraZeneca] vaccine was used to vaccinate older people whereas in Europe people thought initially the vaccine doesn’t work in older people.
“I’m not saying there was any mistake done by anybody, I’m just saying that there’s a lot of data that still need to be made available that we don’t have.”
Soriot added that T-cells – immune cells that both educate antibody-producing B cells about the nature of the viral threat, and directly kill infected cells – might provide some explanation for differences in hospitalisation rates between countries.
He said: “Everybody is focused on antibodies, but antibodies you see them decline over time. This T-cell response remains important. As soon as this virus attacks you, they wake up and they come to your 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.
“What I’m saying is that T-cells do matter and in particular it relates to the durability of the response, especially in older people, and this vaccine has been shown to stimulate T-cells to a higher degree in older people.”
However, Danny Altmann, a professor of immunology at Imperial College London, said it would be extremely difficult to attribute the differential shape of the curves for the surges of infection in the UK and other European countries to any single factor.
“It would be slightly foolhardy to try and attribute that to the quite nuanced differences in choices of vaccine across different countries,” he said. “I don’t know where you’d start to do that scientifically.”