Management of the Coronavirus Outbreak: Oral evidence session
Dea Russell: First, I have a question for Professor Sir John Bell. This might be a lack of understanding from my perspective, but I have read recently that people who perhaps had SARS during a previous epidemic have potential immunity to coronavirus. There were some sort of findings around that. I saw a few articles in Nature. I am interested in your view, from an immunity perspective, on things that might affect immunity for the population more widely.
Professor Sir John Bell: There are three aspects to the immune response. One is the class called antibody-based immunity. We know about that because there has been a big flurry about trying to get tests to measure antibody immunity. Not everyone who has had the virus gets an antibody response, so that is quite an interesting observation. The majority of people do, but not everybody does. It is not clear how durable those antibody responses actually are. There is a cellular response, which is due to T-cells. For other SARS viruses, that is much longer lived. In fact, they can last out to the 20 years since the SARS epidemic, so they are a long-lived form of immunity. Then there is a bit in the immune system called innate immunity, which are cells that live in the mucosal surface and actually attack the virus. At the moment, in our understanding, it looks like many people have existing T-cell immunity to peptides—short proteins—that are expressed in a wide range of coronaviruses, including SARS, and that cross-react. Very often when you get a head cold, it is actually a coronavirus. There may also have been other SARS-type viruses circulating that we do not know about because of the asymptomatic frequency. Those generate a Tcell response that you keep for a very long time. That provides you potentially with some form of cross-immunity to Covid. We do not know that for sure, but that is what it looks like at the moment.
Dean Russell: With that in mind, could it potentially be a reason why places like Singapore, Taiwan, Japan and China have perhaps not been quite as affected in the population, if that turns out to be the case? If they were affected very heavily by SARS previously, perhaps there was a greater immunity in their population.
Professor Sir John Bell: The answer formally is that that is a possible explanation as to why there is quite wide variation in individual bits of the world as to how badly you are hit with the virus. It is whether it is what you have actually done—how tight the lockdown has been and how good your test and trace is—as opposed to how much existing immunity your population might have had to start with. Jeremy would be quite good on this because he spent many years in Vietnam. Vietnam is very odd. They did lockdowns, but they did not do a national lockdown. They did regional lockdowns, and they have had only 300 cases and no deaths in a country of 100 million people. Work that one out. I don’t get it at all.
Dean Russell: Professor Jeremy, would you give your thoughts on that?
Professor Sir Jeremy Farrar: There may be some pre-existing immunity. The data from Singapore that you refer to and that you have read suggests that people who had SARS 17 years ago may have had some protection. SARS was never a widespread community infection. It never reached that level. The background levels of SARS immunity in populations in Singapore and Vietnam, in Hong Kong and in China never reached levels that would protect a population from SARS 2. Other coronaviruses might, and that may explain some of the difference. I think the remarkable success of Vietnam actually has more to do with an incredibly strong public health system. They have been deeply scarred by SARS. A very good friend of mine, Carlo Urbani, died of SARS in 2004 and the whole system was remodelled after that to give a very strong public health system. Although John says that they did not lock down nationally, they introduced some pretty draconian measures—much more draconian than were implemented in the UK. People were put in quarantine. I think there are still 10,000 or 11,000 people in quarantine in hotels or other establishments in Vietnam today. It was much more draconian than has been implemented anywhere in Europe.
Dean Russell: My key question is about the vaccine. There was the announcement yesterday and there have been several announcements over several weeks. I am interested in your take on two points around the vaccine. First of all, I know that there is a big anti-vaxxer movement, which is incredibly dangerous, and is potentially putting people off taking the vaccine. If the vaccine appeared tomorrow and it is all fine, what percentage of the population would need to take it to ensure that the whole population is safe? Secondly, people are just coming into the period when they might be taking their flu jab. Has there been any research into the two working together? What potential risks or benefits are there? Could people have a flu jab and a vaccine together?
Professor Sir John Bell: They are both good questions. Let me start with the latter one first. There has not been any work to date because we are only getting to the point where we know about the Covid vaccines and how they operate. My suspicion is that you will be able to use them both completely safely, but that will obviously need some scrutiny before we can vaccinate much more widely. It is definitely worth keeping an eye on. With regard to what percentage of the population needs to be vaccinated, I go back to a point that I think Jeremy made. With all the discussion about the vaccine, people have thought, “Oh good, the vaccine is going to come; it’s all going to be fine; we’ll all get vaccinated and that will be the end of that.” The reality is that this pathogen is here forever. It isn’t going anywhere. There is so much disease out there. Even if it completely sterilises populations, it is very unlikely that we will eliminate the disease. Look at how much trouble they have had in eliminating, for example, polio. That eradication programme has been going on for 50 years and they are still not there. It is going to come and go. We are going to get winters when we get a lot of the virus back in action. The vaccine is unlikely to have a durable effect that will last for a very long time, so we are going to have a continual cycle of vaccinations, more disease, more vaccinations and more disease. The idea that we are going to eliminate it across the population is not realistic. This is it. It is like the first time we had a big flu epidemic, which was a very long time ago. This is, essentially, the central example of that, and it will be with the human race for a very long time.
Dean Russell: May I express my thanks to you, Professor Whitty, and the team, for everything you have been doing and your momentous efforts over the past few months? My questions relate to the vaccine. There has been some great news this weekend and over the past few weeks about the success in trials. I have a few questions about the practicalities of that moving forward. Do you have a sense of what percentage of the population would need to have the vaccine for it to be truly effective across the country?
Professor Whitty: I hope that Professor Van-Tam is on the line. If he is not, I’ll answer.
Dean Russell: I believe he is. I can see him.
Professor Van-Tam: Good afternoon. You asked how much of the population we would need to vaccinate to have a good effect. I can chop that several different ways, all of which are valid and important. We may end up, in the first instance, with a vaccine that is most appropriately targeted, and with a label that restricts its use, to a certain population; purely for argument’s sake, shall we say those aged over 50? A regulatory body may take that view, and it would always take a view based on risk/benefit. As we know, in this disease the likelihood of death changes very markedly with age, so the risk/benefit for a vaccine is likely to be very different by age. There may be some other considerations—for example, data that show that a particular vaccine does not work in the very elderly or that it has some other limitation. That may constrain who we can give it to. The next point is about how effective the vaccine is going to be. Vaccines range in effectiveness, from flu vaccines, between 40% and 50% in a given year, which seems low, but is a very important public health benefit, to hepatitis B vaccines, which are highly effective. From that perspective, we do not know until we get it how effective it will be. The JCVI has done some work in the area already and, using a new algorithm, has looked at the likelihood of suffering a complicated or fatal outcome from Covid-19, and has looked at the characteristics of patients. If we could vaccinate even the top 20% in the risk scale for adults from the age of 19 to the top end of the range, we would be dealing with the age group in which almost 90% of the mortality is currently loaded. You would only take out all of that mortality if you had a vaccine that was 100% effective, but targeting a relatively small proportion of the very highest risk will deal with a very large number of the population who have the mortality loaded against them at the moment.
Dean Russell: Thank you for that excellent answer. I have a few brief points that I’ll wrap into one question. They are some of the comments that have come into my inbox. First, Professor Whitty or Professor VanTam, do you see a point when it will be a legal requirement to have the vaccine? Secondly, do you see it being free or will a prescription be required? Thirdly, I have heard a lot about the flu jab and that it will shortly be needed for the winter. Do you see an opportunity to combine flu jabs with the vaccine trials?
Chair: We only have time for Professor Whitty, with great apologies to Professor Van-Tam, because we are coming up against the clock.
Professor Whitty: I very much doubt that there would be a legal requirement. Finally, it is a decision for Ministers, but forcing people to have vaccines does not strike me as a good answer under any circumstance. To go back to a previous point that Professor Van-Tam made, we may, in any case, have a vaccine that simply protects the individual but has no benefit to society. In that case, it is entirely a matter of choice as to whether someone wishes to be protected against this substantially significant disease. Whether it is free is a policy decision, but I would expect it to be. If you want more details on combining it with flu, Professor Van-Tam is the expert. If we were lucky enough to get a vaccine in time for the winter flu season, we would of course want to try to do both, but we are some way from that. I want to be very clear. We are incredibly excited by and proud of what the UK has done in leading the way on vaccine science here and on funding vaccines elsewhere. There has been excellent work by many people on securing potential vaccines, but no one should be under any illusions: the chances of us getting a highly effective vaccine before Christmas are, in my view, very low. Professor Van-Tam would probably be a little more optimistic than me, but both of us would say that it was a low probability for this winter flu season.
Professor Van-Tam: I am cautiously optimistic that we will have some vaccine this side of Christmas. If we do, we will not have data on whether it can be given at the same time as flu vaccine, and it is likely that we will have to delay or separate the two vaccines and stage the way we give them to the relevant patients. It is a utopian dream and would be wonderful if one day we could have a combined Covid-19 and flu vaccine in one syringe, because it is the same target group, but that kind of vaccine development will take many years into the future to achieve.
