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Prof. Andrew Pollard: “Why we should forget herd immunity for Covid and vaccine third doses are not inevitable”

prof.-andrew-pollard:-“why-we-should-forget-herd-immunity-for-covid-and-vaccine-third-doses-are-not-inevitable”

Professor Andrew Pollard, new studies suggest that the AstraZeneca vaccine would be a good booster as a third dose. Is this good news for the following months after this terrible pandemic? 

“At the moment, we don’t know if we need booster doses of the vaccine. That’s something that will become apparent in time. We do think that all of the vaccines that are being used here in Europe at the moment are giving fantastic protection against Covid-19. Here in the UK, the latest data have been released showing the impact so far this year of the vaccine program with very, very high levels of real-world evidence of effectiveness, from both the Pfizer and the AstraZeneca vaccine. So the question really about booster doses is two things. One is, will the immune response wane over time? Will people actually need boosting to maintain that protection? We don’t know the answer to that yet. We haven´t had enough time to fully address that question. The second possibility is: as new variants emerge, and they´ll continue to do that over the years ahead, will they find their way around the immune response generated by the vaccines that we have at the moment?

“For both of those, we have strategies. We could boost people with further doses or use new variant vaccines, focusing more on variants that emerge over time. At the moment, here in Oxford, we’ve done a booster study. We haven’t got the results finalized yet, but hopefully, that will happen very soon, and then we can share those. There’s also now, just launched yesterday, a new national study comparing seven different vaccines as boosters here in the UK. Of course, the new variant studies which are going on in the US, and just about started in the UK, will address a similar question, but with a new variant vaccine. So there’s a lot of work going on, but we don’t have all the answers yet.”

So do you think that it’s not inevitable that we should vaccinate the whole population for the third time or in every year in the future, against Covid? 

“I don’t think it’s inevitable yet. We just don’t know. It’s not the same virus as influenza, where everyone is thinking about the flu virus and how that behaves and how it changes every year. Coronavirus is very common in human populations. All of us would have been infected by coronaviruses as children. What happens when we become adults is that we still get mild infections with them. Perhaps last year when you had a cold that was caused by a coronavirus.”

“So despite having immunity from childhood infection, we still get mild infections during adulthood. So it could be that with the vaccine program in place, most people will have enough protection in future years. They would only get the very, very mild infections and be able to carry on without boosters. I’m speculating based on the evidence that we have from other viruses. I think we should be cautious and not say at this moment that we know what the future is like. We have not seen the full behavior of this virus and what it looks like once we’ve got large parts of the adult population immunized.”

However, the U.K. government says that they already have ready the boost for the autumn. 

“Actually, that’s not quite right. What the UK is doing is being prepared. So, if it turns out that booster doses are needed, then the program is in place to do that, but I think there are no decisions on… if it does happen, how many people will be vaccinated? That´s still awaiting emerging evidence. I think we really ought to be driven by science. If science says, perhaps there’s a population of very frail older adults who need to be boosted because they’re losing their immunity, then that would be a really good focus of a program. 

If some catastrophe happens, where the virus completely escapes from the protection we have from the current vaccines, then that would have to be looked at again, and it might happen to be a much wider population. However, I think that scenario is extremely unlikely. I think if anything happens, it’s likely to be focused on those who are particularly vulnerable.

How worried should we be about this new Indian variant and the effectiveness of vaccines against it? 

“I think that focusing on the Indian variant is perhaps the wrong thing to do because it is just one of many variants that will appear in the months ahead. So the question really is whether the vaccines that we have, the programs that we have at the moment, are going to be sufficient to keep people out of hospitals, with the various ones who will emerge over time. I think the evidence we have so far is quite reassuring, that with really severe disease, the vaccines are going to remain highly effective, even with new variants. However, the whole point of the virus throwing up new variants is to continue to transmit to veteran populations. That will include how it can transmit in vaccinated populations. So I think the mild disease or mild infection, asymptomatic infection in the future, even if it doesn’t happen with this variant, future variants will find ways of transmitting and causing those mild infections”. 

“I wouldn’t worry about that, in a sense that finding infections in the population is what’s going to happen in the future. The real question is the one that we haven’t quite got an update from, which is the certainty that the vaccines at the moment will just stop them from going into hospital, at least the majority. But it´s probably a very short time to have that answer, now that the variant first identified in India is spreading here in the UK and other countries: we´ll start to get an idea very quickly about whether the vaccines that have been used are sufficient to stop people getting into hospital. As always, in the pandemics, it’s an evolving story. Everything looks pretty promising at the moment. We are just a little bit early to have certainty.”

The Spanish government has finally decided that it will givesome of its population a second dose of the Pfizer vaccine after receiving the first dose of AstraZeneca. There seems to be some science discussion about it. Do you have any doubts about it? 

“All of the vaccines that we’re using in Europe lead to immune responses being generated against the spike protein of the coronavirus. So if you expose the immune system, despite approaching with one vaccine and then with another vaccine, the immune system will make a response. What we don’t know is what’s the best way around to do it? Studies are needed to try and address how to optimise mixing schedules if that’s the decision that’s made. We don’t have sufficient data yet with adequate controls to answer that question. And that’s what the ComCOV study will answer in the next month or two. But there’s a second issue, which is about how well it’s tolerated. The results, released a week ago, show that at least in older adults when you do a mixed schedule, they tend to have rather more reactions in the first couple of days after they’ve been vaccinated. We don’t fully know why that is, but people feel a bit more unwell with their second dose if you use a mixed schedule. The other point here is that, in younger people,  we know that in general, with all vaccines, they have more short-term side effects. But we haven’t got a study yet in these mixed schedules. So it could be that there´d be slightly worse side effects or even worse in younger adults.”

You said recently that it is morally wrong to keep doses here in the Western countries instead of sending them to countries that don’t even have doses. 

“I think we have to look at all of our populations, not in a nationalistic way. I think that has happened quite a bit over the course of the last year, but to remember that we’re all part of a very interconnected global population. We’ve seen this appalling spread of the virus across South Asia. There’s a huge increase as you move further east into Malaysia, and across Latin America, in cases. Rather like Europe was, you know, a couple of months ago. We’re seeing exactly that and play out in other countries. Very much so, across our nations, increasingly, we have actually vaccinated those older adults. If we decide, as some countries are, to vaccinate very young adults or even children, those doses are very unlikely to make a difference to the survival of those individuals or pressures on the health system.”

“As part of an interconnected community, we really ought to be valuing the lives of those older adults in all of those other countries before we give it to very young people who have almost no risk of the virus. I think this is the moral argument. That if you’ve got someone up near to zero risks of disease, it makes much more sense to protect the individual who’s at very high risk. But there’s other arguments as well. Because at the moment there are many countries where there’s huge rates of disease, there’s no vaccine, and new variants are going to come and they will come back to Europe in the future.”

You mentioned before what you call the nationalistic approach to vaccines and this happened also with AstraZeneca in the dispute between EU and UK, which had a priority on the production of doses. 

“These are important questions, but unfortunately, they are political questions, which are very difficult for me to address because I’m not involved at all in those contract negotiations. But I think the principle is that we really need to make sure older adults everywhere are protected, both in Europe and elsewhere. The question is how do we act together rather than in the domestic interest. Of course, we’re all doing that across All of the rich countries have that focus. But it’s probably not the best way to contain the pandemic, and it’s definitely not the best for most people in the world.”

What do you think about this huge discussion after the US government’s initiative to waive vaccine patents? Do you think that’s a good idea? Do you think it may be counterproductive? 

“I think the idea behind waving patents makes absolute sense: share the intellectual property to have manufacturing sites all over the world, increase the capacity of manufacturing and then be able to save more lives. That is absolutely the right goal. The difficulty with that approach is that we’ve already got commercial interests which will make that difficult to achieve and we’ve seen political differences. I hope that that will be dealt with because we really need to work out a good model of how some form of sharing of intellectual property. To allow wider vaccine production would be good.”

“But if you do achieve that, you then have somewhere between 6 and 12 months to get new sites up and running, licensed, and understand the processes required to make the doses. That is a very complex process. You need very experienced engineers, people to know about manufacturing, to help all of those other sites to learn the technology. I think this is one thing that people often when they come up with these ideas, have not fully understood how difficult it is to make vaccines. This is not like the making of drugs, which are essentially chemicals. These are complex biological materials that are really difficult to make.”

“All of the manufacturers will have some batches that fail, and they´ll have to throw away millions of doses because they don’t pass the requirements. So, this gives you sort of an idea of how complex it is. If you imagine starting today with getting other manufacturing sites everywhere to get going, in a year, we will have a really good supply from them. But it’s not going to fix the problem today. During this month, almost a million people will die globally from coronavirus, and there’s no way that the IP change will fix that.”

“Now, the approach that we took from the university and with AstraZeneca last year, and I think it’s one of the things we’re really proud of, is a deal with AstraZeneca, which meant that the vaccine is distributed not for profit. So that essentially already achieved part of the intellectual property (IP) waiver,  and the second part of the IP waiver that you want to achieve is distributed manufacturing. And AstraZeneca has done that. It set up more than 20 sites around the world. So that’s more than any other developer. And the AstraZeneca engineers are working with all of these sites around the clock to try to get the amounts of vaccine being produced up to the maximum yield so that more doses can be made and save lives. So I think in some ways, by that deal that the university did. I think the very great vision of AstraZeneca to be prepared to come into a partnership, not for profit, has essentially achieved what we would be able to do through the IP waiver, without having to cross that difficult commercial threshold of giving up IP”.

Professor Pollard, what was your reaction to the “almost ineffective” remarks by French president Macron on the Oxford-AstraZeneca vaccine?

“I think in many ways, we know what the data showed. We know the vaccine is highly effective. The data just been released by Public Health England shows that, in the real world, it works just as well as the Pfizer vaccine. We’ve known this all along, that the vaccines are highly effective. Just in this country, we know that over 10000 lives have been saved already from the vaccine program. Now that we’re over 400 million doses distributed worldwide, that will be hundreds of thousands of lives saved globally already.”

“So I sort of feel like we’ve achieved what we wanted to. The problem with the comments the various commentators have made, not just President Macron, don’t so much just undermine the AstraZeneca vaccine: if we undermine immunization, then that has a risk of undermining confidence, and then people are not vaccinated. That also has a risk to them individually. So, I think my biggest concern about a lot of the comments made. and the difficulties that many policymakers have had in working through uncertainty, as data emerge, is that those mixed messages can be quite damaging to confidence in vaccination. And it doesn’t just affect the people in France or people in Germany or Spain or Italy. Those comments affect people and undermine confidence all over the world, because we’re so interconnected.  I think that’s my biggest concern.” 

Professor Pollard, are you also concerned about the blood clots associated with Oxford-AstraZeneca vaccine? 

“here’s a huge amount of work going on by the regulators and by public health agencies both to understand this condition, this incredibly rare event. But also, that if it does occur, to work out how best those patients can be managed, to make sure they have a good outcome. I think the combination of those two things and making sure the public are more aware of the risks has really made a big difference to the perception in many countries.  As far as the words that the regulator uses, I think that for those who live in that world, that’s fairly normal terminology. It’s very difficult to prove causality. Where we are at the moment is that there is this incredibly rare association between vaccination with some of the vaccines, including ours, and this very rare type of clot. It is not just routine clots that people commonly get, but a very rare type.”

“But there are many other things that here in Europe are much more dangerous. And I don’t know if any of you will be getting in your car today, but driving on the roads in Europe is far more dangerous this year than it is to get a clot from this vaccine”. 

What do you think is the level of herd immunity we need to end this pandemic? 

“If we were dealing with a virus that doesn’t change, then the mathematicians could work out what proportion of the population has to be vaccinated to stop the virus in its tracks. We know for measles that you need over 95 percent of people vaccinated. For some other viruses, it may only be 80 percent or 75 percent.”

“But this virus is changing. So, herd immunity for the original strain last year would have been possible. But we’re now dealing with different variants which will continue to emerge and transmit in vaccinated populations. So, I think we should forget herd immunity. It’s the wrong concept because of the variants. The virus will find ways of transmitting in immune populations. In a sense, the real question is what proportion of people need to be vaccinated, that will minimize the number of people going to the hospital, or maybe even stop it completely.”

Professor Pollard, do you think that by the end of the year, we will be able to stop wearing masks and social distancing in the UK and other countries? 

“It’s difficult to be sure because it depends a lot on the extent to which the vaccine program is rolled out, whether there are vulnerable people still around in the population. Unless you have very high coverage in those older adults, there will be people who will get infected and will end up in hospital. And so, I think the public policy is going to have to determine at what point the risk of pressure on the health system, the risk to life has reached a point where it’s safe to do that, and that will be driven in each country by the modellers, and giving some evidence to politicians who then have to make those decisions. In terms of time that there is between now and the end of the year, it’s entirely possible that we could be in a position where we have very highly vaccinated populations, and that could happen. But of course, as we’ve just been discussing, this vaccine hesitancy in some countries and if they’re vulnerable people still out there, we can’t stop wearing masks or the social distancing because they will be put at risk”. 

“The other uncertainty is still the variants. I’ve expressed my optimism, but we don’t know for certain. We need more time to be certain about that. I think it’s interesting to also reflect on how amazingly effective the masks were in preventing influenza last year. Social distancing really works against viruses. So that’s something perhaps for the future. What we do about managing these very serious seasonal outbreaks, the viruses that we have, and that very much affect older adults?”.

So in the case of the UK, despite the huge success of the rollout of the vaccines, is it still possible that we will wear masks and keep social distancing until the end of the year? 

“Well, I’m still waiting. I’d like to hear from Boris Johnson next month about the decision for the 21st of June. So, I don’t know the answer to the question now, but I’m sure the decisions will depend on what happens next. As you say, we’re in an amazingly good place now in the U.K, but there is a new variant circulating, and we don’t have a full understanding of the next step. I understand the politicians being hesitant to answer that question, and I’m not trying to be a politician; I really don’t know the answer. The reason why they’re hesitant is that the data are not yet in. Certainly, over the next month or so, there will be so much more understanding about what variants do in a highly vaccinated population. That’s going to be information useful for all of our countries over the rest of this year and I think that will tell us whether we need to be wearing masks.”

What do you think about travel and holiday at this stage in the UK? Would you make them possible again? 

“I think the problem is the uncertainty of this moment. We’ve seen good protection with the vaccines, even with one dose, with both the Pfizer and the AstraZeneca vaccine. But it’s very difficult to answer the question. If you had two highly vaccinated populations with no virus circulating, well, of course, that’s fine to travel. But I think it´s really for the governments to try and make the policy on doing that.  Whilst there are many transmission and unvaccinated populations, we really don’t want to be vehicles of that transmission ourselves. And so, I would limit travel”.

Do you have any evidence that the risk of those so such rare clots is lesser after the second dose of the AstraZeneca vaccine? 

“The most recent MHRA reports suggest that the rates with the second dose are very, very low. What I can say so far, it looks as if that is the case, that it’s very unlikely in the second dose. It was already pretty low in the first dose, but it’s very much lower doses.”

Do you think that we are actually winning against this virus? 

“I think we’re making huge progress. You could look at individual countries, and you can see this battle is slowly being won. But from a global perspective, we know we’ve just started the war. It’s got so far to go still, but it’s a very worrying situation. It feels in Europe as if we can see the light at the end of the tunnel. But if you’re sitting in some parts of India, it just seems like this is never going to end. I think we have to keep coming back to take a global perspective and to have responsibility ourselves from a global perspective in the way that we need to be more outward-looking now that we’re getting slightly ahead of the curve”.

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