Andrew Pollard: Vaccine rollout, and mRNA promise

Andrew Pollard rounds of his extended interview with us by reflecting on his achievements during the pandemic, and looks to the future with mRNA vaccines...

Chris – What was it like, though, to watch something that you'd developed going out in millions of doses around the world? Effectively, it changed the course of the pandemic. You saved millions of lives, didn't you? What did that feel like? Was it both scary and exhilarating at the same time?

Andrew – That’s a really interesting question. Eventually, over 3 billion doses were produced, and some analyses suggest that over 6 million lives were saved in 2021 alone from the Oxford vaccine. It’s very difficult to connect with what that actually means. One of the problems with vaccination is that people who don’t get a disease and don’t die often don’t realise they've benefited.

To some extent, the work we did during the pandemic – in the lab and in clinical trials – didn’t feel so different from usual. What was different, without any doubt, was the public scrutiny. It’s hard to connect the daily work we did, guided by our usual ethos, to the actual impact it had.
I didn’t personally feel a sense of some amazing achievement. But there were moments – like giving interviews and having people come up and say, “Thank you, you saved my life.” That was very moving. But I certainly didn’t sit around every evening thinking how clever I was – that’s not the approach we take. It’s much more a technical and logistical challenge day-to-day.
Chris – There were some people who suffered severe side effects though, weren’t there? People who developed brain blood clots. Did we get to the bottom of why that happened and why it happened to the people it did?

Andrew – That’s right. It was, fortunately, a very rare event with the first dose of this type of vaccine. And it wasn’t just the Oxford vaccine – another adenovirus vaccine developed by Johnson & Johnson had exactly the same side effect. It’s a rare disorder where individuals can develop clots in certain parts of the body, but unusually this is associated with very low levels of platelets – the blood components involved in clotting.

So it’s almost the opposite of clotting, and that combination sadly led, in some cases, to deaths. The condition appears to vary by region – more common in Scandinavia, less so in the UK, and rare in Southern Europe. We don’t know why that is. There's a general view that there is some unknown reason for these population differences. There are lots of theories, but none are proven.

And they’re hard to test – ideally you’d want an animal model where animals reliably develop the same condition, so you could trial vaccine changes. But we don’t have that. So the cause of this rare condition remains uncertain.

Chris – You must’ve been very excited though when we ushered in the mRNA vaccines, because of the enormous impact they had – not just on the pandemic, but on their potential for other areas of medicine.

Andrew – I think there are two very exciting things about RNA vaccines. The first is just how quickly you can make them at scale. If there were another coronavirus pandemic today, and the supply chains were ready, you could manufacture millions of doses of a new vaccine within six weeks.

By contrast, traditional approaches can take months or years to scale up to that level. RNA vaccine manufacturing is now mature enough that millions of doses can be produced rapidly – a sea change in pandemic response potential.

The second is how easy it is to iterate. You can quickly make many different RNA vaccines in the lab, test them, and find out which works best before moving into human trials – or even give multiple versions to see which is most effective. In one of my areas of work – plague vaccines – we’ve made large numbers of RNA-based candidates over the past couple of years. That would be nearly impossible with other vaccine platforms.