The remarkable progress on a COVID-19 vaccine made by Andrew Pollard, director of the Oxford Vaccine Group and chief investigator on its COVID-19 trials, and his team, holds out hope that an effective and safe vaccine might be available earlier than originally assumed, during 2021. In an interview, he shared insights into the COVID-19 endgame scenarios that might now be on the table. Edited excerpts:Could you explain the vaccine development process of your group, including how the ChAdOx1 nCoV-19 vaccine works, and what phase the trials are in?
The way the vaccine works is rather similar to most of the other vaccines in development. What we are trying to do is induce immune responses to spike protein. The spike protein is the protein that decorates the surface of the coronavirus and the virus uses it in order to enter into the cells in our body to cause infection.
In addition to that, the vaccine also induces a type of white blood cell called T-cells, which are able to destroy our cells if they get infected by the virus. This might halt the infection. The combination of those two is exactly what we hope to induce with the vaccine. We are now in the Phase 3 trials, with more than 10,000 people around the world getting vaccinated.
On the question of efficacy of the vaccine, is it possible that mutations of the virus might render the vaccine less effective than what was seen in the trials?
We do not know the answer to that yet. So far, we do not see evidence that the spike protein itself has mutated so that the vaccine would not work. But that is something that has to be monitored, because these viruses, as they pass on from person to person, they do make mistakes in their genetic code. That could allow these mutations to arise and for new forms of spike protein to develop. One of the reasons why this may not have happened so far, as far as we can see, is that if they have big mutations in the spike protein, they would not be able to infect our cells any more and it would be a dead end for the virus.
How strong was the immune response that you observed in the vaccine trials, and is it something that would inspire hope?
We do not know how strong an immune response is needed for protection. All we can say is that we are seeing immune responses that are better after a second dose. They are also not so bad after a first dose. We do not know if those are enough for protection, which is why we have to do these trials.
How much protection will the vaccine offer? Will the effect be uniform across the population?
It is likely that there will be differences in immunity between people. A particular hurdle is for older adults, especially those over 70 years of age, where we know that their immune systems just do not crank up as much when they are vaccinated.
India is expected to have possibly the world’s largest number of COVID-19 cases by early 2021 — once the vaccine has been rolled out to scale, how long will it take to bring the pandemic to a halt?
We need to have enough doses of the vaccine available, and then we need to be able to vaccinate enough people to stop the virus in its tracks. But that is quite a big deal. First of all, you have got to manufacture it at an enormous scale, for a country like India, to be able to vaccinate a large proportion of the population.
Then you actually have to get out and deliver the vaccine on a scale that has never been seen before. That is also a big hurdle. Even if you have a vaccine and you have enough doses, the logistics of preventing infection in everyone is going to be a huge, mass vaccination programme.
Many countries are thinking, initially, about how to protect those at greatest risk, like hospital workers, older individuals, and those with co-morbidities. That is probably the right way to start.
From your perspective, given the science that has gone into vaccine development, what would a reasonable price for the vaccine be?
I do not know what the price range would be. I did hear Adar Poonawalla of the Serum Institute of India speaking about some suggested prices but the important thing for most people in the world is that governments are likely to pay for this or have funding externally from international organisations to help them. So, hopefully for individuals being vaccinated, this will be of no cost to them, or a very low cost.
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