Decisive use of AstraZeneca vaccine may have spared UK from omicron crisis hitting Europe

Britain’s relatively low recent death toll from Covid compared to Europe may be a result of earlier use of the Oxford/AstraZeneca jab to vaccinate the most vulnerable, according to the nation’s former vaccine tsar.

Dr Clive Dix, former chairman of the Vaccine Task Force, told The Telegraph that he believed the AstraZeneca jabs offered more robust, long-term protection against severe disease and death than RNA-based alternatives made by Pfizer and Moderna.

Britain’s Covid death rate has been relatively flat for several months, and there has not been a noticeable surge in Covid deaths due to omicron.

However, many European countries have recently seen steadily increasing death rates and have more Covid deaths on a like-for-like basis than the UK.

Figures from Our World in Data, a website run by the University of Oxford, shows the UK has 1.7 daily deaths from Covid per million people. In comparison, the EU as a whole has almost four.

“If you look across Europe, with the rise in cases, there's also a corresponding lagged rise in deaths, but not in the UK, and we have to understand that,” said Dr Dix.

“I personally believe that's because most of our vulnerable people were given the AstraZeneca vaccine,” Dr Dix said.

The key, he says, is that although the RNA jabs produce a more obvious and rapid jump in antibody levels in lab tests, other vaccines may be better at priming another part of the immune system: cellular immunity.

Cellular immunity includes various forms of T cells, including those that destroy infected cells, and also memory cells, ensuring a person can fight off an infection several years after they are first exposed to it. They are slower to react than antibodies and do not prevent infection, but do halt the pathogen in its tracks, making it harder for the virus to cause damage.

“We’ve seen early data that the Oxford jab produces a very durable cellular response and if you’ve got a durable cellular immunity response then they can last for a long time. It can last for life in some cases.” he said.

The only notable difference, he said, between the UK and Europe’s vaccine rollout was the approach to the AstraZeneca jab.

While Britain used its ample stock to rapidly inoculate the oldest and most vulnerable people, officials on the continent besmirched the vaccine’s reputation and dragged their heels on its approval, opting instead to wait for the Pfizer vaccine.

MRNA vaccines like those made by Pfizer are based solely on the spike protein of SARS-CoV-2, the virus that causes Covid-19, and produce highly specific antibodies. But AstraZeneca, and other jabs like those made by Novavax and Valneva, used a more well-rounded approach, said Dr Dix.

“We know that with adenoviral vector vaccines and adjuvanted proteins you get a much broader cellular response and I think we need to look at all that data across all the vaccines,” said Dr Dix.

He added that there was “nothing wrong” with using Pfizer or Moderna as a booster, but alternative vaccines may be a better alternative in the long-term.

Lab results 'don't always translate to the real world'

The decision to move away from giving a primary dose with AstraZeneca and to only use Pfizer or Moderna for boosters was based on various data, including a major study that showed Pfizer and Moderna to be the most effective. But how these lab results translate into real-world effectiveness remains to be seen.

“I think we're getting a little bit ahead of ourselves by just measuring antibodies and neutralising antibody responses in the lab as that doesn't follow through for serious disease and death,” said Dr Dix.

“If you look at all the data, there isn't a great correlation between neutralising antibody lab results and protection from severe illness and death, they don't seem to correlate.

“And that's almost certainly because the cellular immune response is the important thing to stopping serious illness and death.”

The lab-based studies had also thus far failed to suitably measure T cell levels over time, something Dr Dix says needs to be urgently addressed if we are to establish the best jabs for annual boosters, which he thinks will be needed for the over-50s and the vulnerable, much like they are for flu.

“[The T cell analysis method used in most studies] just tells you that there are some T cells in the blood that do recognise antigens in the virus.

“It doesn't tell you very much about the quantity or the quality of the responses and it doesn't differentiate between the different T cell classes very easily.

“I do think we've lost the battle with transmission. There's no vaccine that is going to change that. I think we should focus on the cellular immune response, and it may just get us out of the woods.”