Archive for Dr. Catherine Schuster-Bruce

A top scientist explains why a more infectious coronavirus variant is a bigger problem than a deadlier strain

coronavirus hospital
A nurse puts on her Personal Protective Equipment before tending to a COVID-19 patient on October 21, 2020 in Essen, Germany.
  • The deadly coronavirus that's spread across the world has mutated. One variant, called B.1.1.7, is more infectious, and has forced the UK into national lockdown.
  • The variant has also been discovered in multiple US states, and in other countries around the world.
  • The variant does not appear to be more deadly, and experts believe existing vaccines should work against it.
  • But Adam Kucharski, assistant professor at the London School of Hygiene and Tropical Medicine, said that, in general, a variant that's 50% more transmissable is a bigger problem than a variant that's 50% more deadly.
  • "A really severe disease that one person gets won't necessarily have as much impact as a 'sometimes-severe' disease that a huge number of people get," he told Business Insider.
  • Visit Business Insider's homepage for more stories.

The new, more infectious coronavirus variant first discovered in the UK could potentially deal more damage than a variant that is more deadly, a leading public health expert has warned.

SARS-CoV-2, the coronavirus that has spread across the globe like wildfire and killed 1.85 million people worldwide has mutated, and experts believe the new variant, B.1.1.7, is much more infectious.

Scientists say this variant is to blame for the surging numbers of people infected with the virus in the UK, which has seen hospitals filling up with COVID-19 patients, forcing the UK into a national lockdown. UK government advisors said on December 18 that the UK variant has a roughly 71% higher growth rate than other variants. The growth rate is how quickly the number of infections changes daily.

Early studies led by researchers at the London School of Hygiene and Tropical Medicine suggest the variant is unlikely to cause more serious illness, and experts have said vaccines should still work against it. But according to Adam Kucharski, associate professor at the London School for Hygiene and Tropical Medicine, the fact the variant is more easily spread means it is potentially more dangerous than a deadlier strain would be.

Kucharski, a scientific advisor to the UK government, tweeted on December 28 that a SARS-CoV-2 variant that's 50% more transmissible would, in general, be a much bigger problem than a variant that's 50% more deadly. 

In an interview with Business Insider on Monday, Kucharski explained his maths and described what he thinks needs to happen next.

Adam Kucharski London School of Hygiene and Tropical Medicine assistant professor headshot
Adam Kucharski, associate professor at the London School for Hygiene and Tropical Medicine

Questions and responses have been lightly edited for clarity

Dr. Catherine Schuster-Bruce: What were you trying to say with your tweet?

Adam Kucharski: I think for me the key message is getting people to understand how much more of a problem an increase in transmission is, especially when we're so close to being able to vaccinate a whole bunch of people.

CSB: Can you explain the maths?

AK: A general principle for every disease out there is a variant that is 50% more transmissible would, in general, be a much bigger problem than a variant that's 50% more deadly.

I think the point is, a small risk of death with a very large number of people infected, means more deaths than a slightly higher risk of death amongst a much smaller outbreak. A really severe disease that one person gets won't necessarily have as much impact as a 'sometimes-severe' disease that a huge number of people get. It's a trade-off between how many people get it, and what the impact is.

Given where we are with this coronavirus and the fact we've got vaccines, the question is around what the impact is going to be in the window before vaccines become useful. In that situation, higher transmission is, in general, going to be a much bigger problem than the equivalent change in intensity - even if it's not more severe, you end up having more impact than a virus that's spreading more slowly.

CSB: The same principles would apply in the US and the UK?

AK: Yeah, because essentially they're referring to the underlying epidemic that's happening, which in reality, we just measure a glimpse of with testing.

CSB: Would an infectious disease expert or genomics expert agree with you?

AK: Well, I hope so. I think it depends. I mean, there's obviously uncertainty around the exact values here, but I think we've got a clear surge in spread in the UK. So even if it turns out to be something else, you've got that increased transmission, which is an enormous problem when you've got a vaccine on the horizon.

Even if it turns out that some component of it was behavior and another component was changes in the virus, that's still an increase in transmission, which is going to be an accelerating problem to deal with.

I think increasingly there's consensus that something unusual is going on here. If it's genuinely 50% more transmissible, we've got a real problem.

CSB: Do we know whether the variant causes less severe disease?

AK: We don't currently. There's not a perfect study at this point that can give us a complete answer.

And there's nothing that's emerged that points strongly to this [variant] being far more severe, but there are now quite a few evidence threads that suggest it is more transmissible. In turn this means that you're going to get more infections with more impact.

Read more: Scientists are investigating whether the new COVID-19 variant is more infectious in kids. Here's what we know so far.

CSB: Why is there a difference in the numbers of people with the variant in the US?

AK: One of the most obvious differences is the ability to sequence the virus to find the variant. In the UK about 5% of all cases that get tested positive are being sequenced, and that's much smaller in the US. It doesn't mean there aren't people infected with the variant, it just could mean they haven't found it. If it's indeed spreading much faster, by the time you start to spot it, you've already got a very big problem.

CSB: Does the theory account for other factors that could impact how the virus transmits from one person to another, like socializing for example?

AK: We've seen in the UK that this new variant has come up really dramatically through Autumn - even in places where there was quite a lot of infection already, this strain has really come up faster. So it's completely accurate to say that it's spreading faster than [the variants] already there.

The question is whether it's spreading faster because the inherent property of the virus, or does it just happen to be in groups that for some reason are behaving in a way that's generating more transmission?

I think particularly at the start, that's always the thing we have to watch out for, but I think there's been this accumulation of evidence that it becomes harder and harder to see it purely as a behavioral aspect. It's more and more likely that there's something different about this virus that's making it easier to spread.

In particular one of the UK studies that was all preliminary but came out of Public Health England, suggested it wasn't just that people with this variant are having more contacts, it actually seems that for every contact they have, there's a higher risk. This again, is another indication that might be something to do with the virus.

So of course we have to be careful about generalizing and I think I'm always a bit cautious about it sort of saying, it's "56%" or whatever, more contagious. I think we have to put quite a bit of uncertainty around that, but ultimately if it's 30% more contagious or 70% more contagious, both of those are a massive problem.

CSB: Could the variant be a scapegoat for people not following the rules?

AK: I think there's always that chance that there's an element of behavior to what's going on. But I think that the patterns we're seeing have become increasingly hard to explain that it's just to do with behavior.

What would generally happen in the data is you'd get this kind of 'dilution effect.' Say by chance, a new variant that didn't have any intrinsic differences got into a population that just weren't following the rules, and there was a lot more transmission in that group. That variant would start to rise in prominence because you'd have more transmission in that group, but then it would get out into the wider population where there's other things circulating and into other groups that aren't necessarily spreading more. So you'd start to expect its prominence to 'dilute', and it wouldn't necessarily become dominant in every group, across every part of the country.

I think the key thing to watch is what happens in other European countries. Denmark, for example, are sequencing more and more. Based on what we see in the UK, we think [the variant] should become more and more prominent. If this is genuinely [71%] more transmissible, this is going to be a big problem for any other European country that has it.

Read more: A new variant of coronavirus has sparked panic and travel bans - but experts say COVID-19 vaccines should still work against it. Here's why.

CSB: Are there any other like stats or misconceptions that you think would be useful to demystify?

AK: I think the one throughout has been the challenge that by the time you're seeing a massive impact of an infectious disease, you haven't got a problem. You had a problem weeks ago, it wasn't tackled and you're only now seeing the impacts of this.

CSB: From your point of view, what do you think the main challenge now is?

AK: An enormous challenge in any epidemic is people's behavior. We've seen in some countries, the level of restrictions might be quite similar on paper to what they were earlier in the year. But then if you look at human mobility data, people are interacting and going around a lot more. So that's just a change in behavior relative to what's going on.

I think we've also seen in the US and UK in some areas when epidemics get quite large and hospitals start getting overwhelmed, people will change their behavior, even if they're not being told to. If you've got a massive epidemic in your community, quite clearly, you're not going to go about your daily business as if there's nothing going on.

It's also quite difficult to work out the impact of measures. We saw in the UK that some of the measures in November didn't have the same impact that the March/April measures had.  To what extent this is because specific things were opened or closed, or just because people are now behaving very differently because we're nine months into a pandemic, is a challenge to work out.

covid vaccine trial
Model Lisa Taylor receives a COVID-19 vaccination, as she takes part in a vaccine study at Research Centers of America on August 07, 2020 in Hollywood, Florida.

It needs to be measures combined with government action, because a lot of [the impact] isn't just people not going to work to stop the virus spreading, for example. If people don't go to work then that has implications for them. If the schools are closed, it has implications. And so, I think government does have a role to make sure that that kind of damage is mitigated. There's huge implications for things like inequality. It's clearly not a level playing field in terms of some of these impacts. I think governments have an important role to try and work out how to reduce the damage of those things.

The balance of actions is very different to what it was earlier in the year because we have a vaccine on the horizon. Essentially a vaccine gives us an ability to massively cut the hospitalization and fatality rate of this virus. That opportunity is certainly - in the US and Europe - about two or three months away.

I think there's potentially a much stronger argument to be made for preventing infections and their impact now, because those are going to be events that you're going to potentially prevent forever, because those people will then be vaccinated.

CSB: Do you think that this new variant is so transmissible that any lockdown measure isn't going to work?

AK: I think that's the key question. I think it is a massive difference that we have vaccines available because that really gives a clear incentive that we're not taking action with some uncertain future. I think we really need to bear that in mind with what happens next.

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The coronavirus variant in South Africa seems to evade antibody drugs, which is ‘very concerning,’ ex-FDA chief Scott Gottlieb says

dr. scott
Former FDA Commissioner Scott Gottlieb with Margaret Brennan on "Face the Nation" in Washington, DC, on March 8.
  • Dr. Scott Gottlieb, the former Food and Drug Administration commissioner,  said Tuesday that a coronavirus variant identified in South Africa was "very concerning" because it might get around antibody drugs that try to help the body fight infection.
  • Speaking on CNBC, he said evidence from the Seattle-based Bloom Lab, which hasn't been peer-reviewed, suggested that the variant in South Africa could partially escape antibodies that fight the coronavirus.
  • This means antibody drugs used to treat COVID-19 — or the antibodies in someone previously infected with the coronavirus — might not be effective against the new variant, he said.
  • No cases of the variant, which appears to be more infectious and is known as B.1.351 or 501Y.V2, have been detected in the US.
  • Visit Business Insider's homepage for more stories.

Dr. Scott Gottlieb, the former head of the US Food and Drug Administration, has warned that a coronavirus variant identified in South Africa may evade antibody drugs that treat COVID-19.

Speaking on CNBC on Tuesday, he said that early evidence from the Seattle-based Bloom Lab, which hasn't been peer-reviewed, suggested that the new variant could partially escape antibodies that fight the coronavirus.

This means drugs that use antibodies from someone previously infected by the coronavirus might not be effective against the new variant, known as B.1.351 or 501Y.V2, he said.

No cases of the variant, which also appears to be more infectious, have been detected in the US.

Gottlieb said the US was in a race against time to get vaccines into people's arms before new variants became more prevalent.

"We don't know exactly because we don't know exactly how this variant has behaved in people who have been treated with these different approaches," he said, adding: "Vaccines can become backstop against variants really getting a foothold here in the United States, but we need to quicken the pace of vaccination."

A different fast-spreading coronavirus variant, known as B.1.1.7 and first identified in the UK, has been detected in several US states and has most likely been circulating for several weeks.

Gottlieb: Stockpile fewer vaccines to make them more available

Gottlieb did not advocate changing the vaccine schedule - for example prioritizing the first dose, as the UK has done - but instead pushing out more vaccines to the public. He said this could be done by "taking a risk" and stockpiling 25% of the vaccine doses that are manufactured, rather than 55%, to make more doses available.

It's normal for viruses to mutate over time, and eventually certain combinations of mutations can create new variants. The variants identified in South African and the UK are causing concern because they have an unusual number of mutations including in the spike protein, the part of the virus that binds to human cells to infect them. It's likely that this makes them more contagious.

The variant in South Africa has also been associated with a higher viral load, or higher concentration of virus particles in the body, possibly contributing to higher levels of transmission, per Reuters.

Read more: AstraZeneca's vaccine is expected to work on new COVID-19 strains, CEO says

Scientists are still investigating exactly how the different mutations change the virus' behavior, including whether the vaccines available will work against them. Experts have predicted that vaccines will still work against the variant identified in the UK, but it's less clear for the one in South Africa.

John Bell, a professor of immunology at the University of Oxford, told Times Radio on Sunday that there's a "big question mark" as to whether vaccines would work for the variant in South Africa because there's not much information about it.

Richard Lessells, an infectious-disease expert at the University of KwaZulu-Natal, is investigating that question. He told the Associated Press on Monday that this is "the most pressing question facing us right now." 

Read the original article on Business Insider

The UK is considering whether it can speed up COVID vaccination by giving everyone only one dose of the vaccine

covid vaccine trials south africa
A volunteer receives an injection for a potential vaccine against COVID-19 in South Africa.
  • Ex-British prime minister Tony Blair said on Wednesday that the government should give people one shot of the COVID-19 vaccine instead of two, so people can be immunized more quickly to curb the spread coronavirus.
  • One dose has a 91% effectiveness rate. The second dose raises the rate to 95%.
  • Professor David Salisbury, former head of Immunization at the UK Department of Health, backed the idea: "You are only gaining 4% [extra protection] for giving the second dose," he said.
  • Some scientists said Blair's idea was too risky, given the minimal trial data on how well the vaccines work with a single dose.
  • The UK government is looking into the option of one dose, an unnamed source told The Telegraph.
  • Visit Business Insider's homepage for more stories.

The British government is in talks with the UK medicines regulator after former UK prime minister Tony Blair called for the government to give everyone a single shot of the vaccine instead of the recommended two doses, according to The Telegraph.

Pharma giant Pfizer's shot is the vaccine currently licensed for use in the UK, US, Canada and Europe. It is legally approved to be given in two doses, 21 days apart.

However, there is a debate over whether it would be more efficient to roll out a single-dose shot first, and then worry about the second recommended dose later. 

The logistics of giving everyone two doses, sequentially, are daunting:

  • Prioritization takes time: All countries have had to prioritize who gets it first. There are also logistical challenges - Pfizer's vaccine has to be stored at very cold temperatures, for example. Seven-hundred-and-forty-thousand people have been injected with their first dose of Pfizer's vaccine, and more than 2.4 million people have been immunized worldwide, according to Our World in Data on Wednesday.
  • It takes months: The current UK strategy, developed with the Joint Committee on Vaccination and Immunisation, puts those most at risk of severe COVID-19 first in line - older people and healthcare workers. But it could be months before the entire population is immunized.

To speed up the process, Blair said that instead of giving people two shots, all available vaccine stock should be used to immunize people with their first dose, rather than giving people already immunized their second. (His suggestion is part of a multi-part plan that he has drawn up, that also urges the UK government to prepare controversial health passports.)

Pfizer has said the vaccine was 95% effective at protecting against COVID-19, 28 days after the first dose, when two doses were given in trials.

But Professor David Salisbury, former head of immunization at the Department of Health -  speaking on BBC Radio 4 on Wednesday - noted that a single dose can also be highly effective.

"You give one dose you get 91% [protection]. You give two doses and you get 95%. You are only gaining 4% for giving the second dose," Salisbury explained.

"With current circumstances, I would strongly urge you to use as many first doses as you possibly can for risk groups and only after you have done all of that, come back with second doses," he added.

He did, however, acknowledge that the same principles do not apply to AstraZeneca's COVID-19 vaccine - that could be UK-approved imminently - because the efficacy of two doses is lower, at 60%. 

Too risky? Or good sense?

University of Oxford's Professor Peter Horby, the UK government's New and Emerging Respiratory Virus Threats Advisory Group - NERVTAG chair - told the Commons select committee on Wednesday that you can't assume one dose is as good as two doses. The current data favours two doses. He also said that we don't know how much of the population has to be immunized with one dose to reduce the spread of virus. 

Professor Wendy Barclay, head of the Department of Infectious Disease at Imperial College London and NERVTAG member said that the idea was interesting, but "too risky".

"To change at this point, one would have to see a lot more analysis of clinical trial data," Barclay said.

However, there are experts that see some benefits to Blair's plan. "Live conversations" are now going on between the UK government and regulator, per The Telegraph.

Professor Peter Openshaw, professor of experimental medicine at Imperial College, London, told the Telegraph on Wednesday that the move would go against normal practice but did make "good sense", but it was unclear how long immunity would last if people are given just one dose.

"It does make sense immunologically that a highly effective vaccine might only need one dose, but the durability of the protection is unpredictable," Openshaw said.

"A booster might be needed subsequently to enhance responses and make them last longer," he added.

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The UK approved Pfizer and BioNTech’s COVID-19 vaccine, the first Western nation to give it the green light

A woman holds a small bottle labeled with a "Vaccine COVID-19" sticker and a medical syringe in this illustration taken April 10, 2020.
Vaccines can't be rolled out in a country until its drug regulator has scrutinized and approved it.
  • The UK regulator on Wednesday approved a COVID-19 vaccine made by the US Pharma giant Pfizer and German biotech BioNTech.
  • The approval makes the UK the first western nation to approve one of the several vaccines in the late stages of development.
  • The UK government said that the vaccine will be made available next week.
  • Pfizer and BioNTech started developing the experimental shot in March. Usually vaccine research takes several years.
  • Vaccine frontrunners AstraZeneca and Moderna have submitted trial data for their COVID-19 vaccines to regulators, but they haven't been signed off.
  • Visit Business Insider's homepage for more stories.

The UK has become the first Western country to officially have a new coronavirus vaccine, the government announced Wednesday.

The country's regulatory body, the Medicines and Healthcare products Regulatory Agency (MHRA), gave its approval to the vaccine developed by US drugmaker Pfizer and the small German firm BioNTech.

In a press release, the government said that the vaccine would be available within a week.

It said: "The Government has today accepted the recommendation from the independent Medicines and Healthcare products Regulatory Agency (MHRA) to approve Pfizer-BioNTech's COVID-19 vaccine for use.

"This follows months of rigorous clinical trials and a thorough analysis of the data by experts at the MHRA who have concluded that the vaccine has met its strict standards of safety, quality and effectiveness."

The UK has ordered around 40 million doses. Officials have said that healthcare workers, the elderly, those in care homes, and people with other medical conditions making them vulnerable to COVID-19 will get priority.

Matt Hancock, the UK minister in charge of the healthcare system, said of the news on Twitter: "The NHS stands ready to start vaccinating early next week. The UK is the first country in the world to have a clinically approved vaccine for supply."

The MHRA said that Pfizer's vaccine protects against COVID-19 — the disease caused by coronavirus — and is safe, after it reviewed all the vaccine's data including from a large, late-stage clinical trial of 43,661 volunteers. 

Pfizer submitted the data to the regulators on 23 November, after it announced preliminary results that its vaccine was 95% effective.

The turn-around from the MHRA has been unusually quick, with regulators in other countries — including the FDA, EMA and authorities in Canada, Japan and Australia — still scrutinizing the data.

Pfizer's vaccine is a new mRNA technology that uses genetic material to stimulate the immune system to protect against coronavirus infection.

The regulatory approval in the UK marks a milestone for Pfizer, but also for other vaccine-makers, like Moderna, that use mRNA technology too. It signals that similar vaccines could work safely and effectively too.

Read more: How the pharma giant Pfizer teamed up with a little-known biotech to develop an effective coronavirus vaccine in record time

Pfizer and BioNTech themselves plan to deliver 50 million doses across the world by the end of 2020, with production ramping up to produce more than 1 billion in 2021. 

The supply chains to get the vaccine to those who need it are already in place in the UK, authorities said. They include designated "hubs" that can store the vaccine. It requires ultra-low temperatures for shipping, and then can be stored for up to 5 days in a normal vaccine fridge.

Read more: Drugmakers behind 3 coronavirus vaccines say they work. Here's everything we know about the race for a vaccine and when you might be able to get a shot.

The milestone approval is significant, but it's just the start. In order to end the pandemic, roughly 80% of the global population vaccine must be immunized.

"Finding a vaccine is not going to end the pandemic overnight, but we are hopeful of being one step closer to defeating this terrible virus," said UK Business Secretary Alok Sharma.

The vaccine is given as two shots, two weeks apart, and experts have already raised concerns about people returning for the second shot, especially if they get side-effects.

Scientists are also in the unusual position of learning about a disease at the same time as they're creating vaccines against it. They're still investigating how long the vaccine's protection lasts for, and whether additional shots will be required. It's also unclear whether it stops people from spreading the virus to others. 

Above all, we don't know how well Pfizer's vaccine will work in real life. However, tracking its use in millions of people is the only way to figure this out. And there's added benefit that this knowledge could be applied to other harmful diseases.

"Pretty soon the question 'Why only COVID?' will come," Albert Bourla, Pfizer's CEO said at a Goldman Sachs healthcare conference. "If we prove that you can make vaccines in less than a year, OK, why can't we do that with other medicines, with cancer medicines?"

Read more: Pfizer's top scientist tells us the pharma giant is already thinking about a new version of its coronavirus vaccine for 2021 that can overcome one of its biggest limitations

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Here is how seriously to take high-profile criticisms of AstraZeneca’s vaccine trial

coronavirus vaccine UK
Kate Bingham, a UK government official, after being vaccinated in London in October 2020. She did not take the Oxford/AstraZeneca vaccine.
  • Oxford University and AstraZeneca announced on Monday that their vaccine works — but the story soon got messy.
  • AstraZeneca's Mene Pangalos said a group of study participants received a lower dose by accident, prompting a wave of criticism from experts.
  • There are legitimate reasons to criticise the vaccine, questioning details of the development process and its precise effectiveness.
  • But it is important not to overhype the problems — the vaccine has been proved safe and could become a powerful weapon against COVID-19.
  • Visit Business Insider's homepage for more stories.

AstraZeneca and Oxford University's high-profile announcement on Monday of a working vaccine has soured in the days that followed.

After promising headline results, it became clear that the development process had been less than perfect, with some participants mistakenly given a smaller dose, which appeared to actually make it more effective.

On Thursday, after a wave of criticism, its CEO admitted there were problems in the process and pledged to run another study. It is a markedly less smooth launch than rival vaccines from Pfizer and Moderna.

The issues prompted critical columns and a wave of attacks on social media. But it is important to take the news in context.

What AstraZeneca is rightly being criticized for

  1. AstraZeneca and Oxford made a mistake — the lower doses were given by accident and the trial was never meant to measure what that achieved, making it harder to know how good the vaccine truly is at that dose.
  2. They have not published much detail on their trials — less than Pfizer or Moderna. This means skeptics and critics have more ammunition. (No vaccine-maker has published a peer-reviewed journal paper, which is the gold standard.)
  3. AstraZeneca's data is more complicated from the start. Its results are from three separate trials in the UK, Brazil and South Africa, rather than from one big study like Moderna and Pfizer. They had different start dates and used different placebos.
  4. The company took several days to respond and commit to undergo another study.
    Mene Pangalos AstraZeneca's head of innovative medicine
    Mene Pangalos, AstraZeneca's Executive Vice President of BioPharmaceuticals Research and Development.

Why not to give up hope

  1. Scientists always criticise each other's work — it's how processes are refined and progress happens. For brand new problems like the COVID-19 coronavirus this is especially so.
  2. Scrutiny like this is part of the process, and needs to be intense because so much is at stake.
  3. It is easy to overhype criticisms, and feed unfounded fears of vaccinations.
  4. The results so far suggest that the vaccine works against COVID-19, even if it may take longer to work out exactly how well.
  5. The vaccine has significant advantages over its rivals — it is cheaper and is much easier to store and transport — which could ultimately help it reach patients that the other vaccines can't.
  6. Mistakes are not always a disaster — for instance penicillin was discovered accidentally.

When you're promising a solution to a serious pandemic that's caused 1.4 million deaths across the world, it's inevitable that the stakes are high. There's legitimate reasons to speak out, but also a balance to strike.

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Scientists are puzzling over one crucial number as they evaluate the Oxford-AstraZeneca coronavirus vaccine

astrazeneca covid vaccine
Oxford-AstraZeneca's vaccine could be given at half-dose initially.
  • The Oxford-AstraZeneca vaccine candidate is 70% effective, on average, according to a press release published on Monday.
  • The vaccine is given as two shots. Efficacy increased to 90% in a smaller group of volunteers who received a half dose in the first shot, then a full dose in the second shot.
  • Experts including Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, are puzzling over the unexpected result.
  • Visit Business Insider's homepage for more stories.

The long-awaited early results from the University of Oxford and AstraZeneca's COVID-19 vaccine trials are in — and experts are puzzling over one big question.

The headline is that the vaccine works. Oxford and AstraZeneca said that the vaccine is 70% effective at protecting against COVID-19.

However, that 70% figure is an average of two efficacy numbers from different tests of the shot, one of which showed the vaccine is 90% effective. Now doctors and scientists are trying to understand how effective the shot really is, and how it stacks up against rival vaccines.

Moderna and Pfizer have both reported that their vaccines are about 95% effective at preventing COVID-19, though each trial measures the figure differently.

The Oxford-AstraZeneca vaccine candidate is given to people as two doses, at least one month apart. The trial data, which comes from late-stage studies in the UK, Brazil and South Africa, suggests that the vaccine is 62% effective if people get two full doses, but 90% effective when they get a half-strength version of the first dose. 

The information was provided in a press release and hasn't been published in a peer-reviewed journal. AstraZeneca and Oxford said they're submitting the results for review and publication.

Britain's William, Duke of Cambridge, wears a mask as he meets scientists during a visit to the manufacturing laboratory where a vaccine against the coronavirus disease (COVID-19) has been produced at the Oxford Vaccine Group's facility at the Churchill Hospital in Oxford, Britain, June 24, 2020. Steve Parsons/Pool via REUTERS
Britain's William, Duke of Cambridge, visits the Oxford Vaccine Group's facility at the Churchill Hospital, in Oxford.

'Digging into the details'

The University of Oxford team doesn't know the exact reason for the differing efficacy figures, but plans to investigate it further, Sarah Gilbert, a professor of vaccinology who leads the Oxford team, said at a press conference on Monday.

"We'll be digging into the details of exactly why we get better efficacy with half-dose, full-dose," she said.

Gilbert said that it may be that the half-dose regimen, "better mimics what happens in a real infection."

"It could be that by giving a small amount of the vaccine to start with and following up with a big amount, that's a better way of kicking the immune system into action and giving us the strongest immune response, and the most effective immune response," she said.

About 2,741 participants in the trial got the half-strength version of the shot first, and all were in the UK, AstraZeneca said.

Dr. Andrew Pollard, director of the Oxford Vaccine Group, said that Oxford scientists originally thought two high doses would cause the best response, and so Pollard said the results are "intriguing." 

Researchers may adjust the US trial to test the half-strength vaccine

Katie Ewer, an associate professor and senior immunologist at the Edward Jenner Institute for Vaccine Research is a key member of the Oxford vaccine team. 

She told Business Insider that it's too late to use these results to make changes to the UK trial. But the researchers may try to test the lower dose strength in the big late-stage study that's currently signing on volunteers in the US, she said.

"They may well decide to look at the low-dose, standard-dose, or they might decide to look at low-dose, low-dose," she said.

Pollard acknowledged that there may be some difference in the effectiveness of the Oxford-AstraZeneca shot and rival vaccines 

But he said it's too soon to say for sure, and he noted that each trial makes different decisions, for example about how to measure efficacy, making it difficult to compare figures from different trials. 

There's likely to be a lot of demand for coronavirus vaccines

Still, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told STAT News that he's worried about who would get each vaccine, should the Oxford-AstraZeneca shot turn out to be less effective.

"If it's 70%, then we've got a dilemma," Fauci said. "Because what are you going to do with the 70% when you've got two [vaccines] that are 95%? Who are you going to give a vaccine like that to?"

Different vaccines have unique characteristics and will likely be used in different places and populations. For example, preliminary results suggest Oxford-AstraZeneca's candidate works best in older adults. It also doesn't need ultra-cold temperatures so it might be the best option for middle and lower income countries who can't afford cold storage, and it's less expensive.

Furthermore, there's likely to be a lot more doses available of the Oxford-AstraZeneca Vaccine than of Moderna's or Pfizer's. AstraZeneca said it plans to be able to make up to 3 billion doses next year.

For now, there will be more than enough demand for any of the vaccines, AstraZeneca CEO Pascal Soriot said on Monday.

"If you add the capacity that Pfizer has announced, plus the Moderna announced capacity, plus our capacity, which is much bigger, the 3 of us don't even have enough vaccine production for the world," he said.

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Scientists are puzzling over one crucial number as they evaluate the Oxford-AstraZeneca coronavirus vaccine

astrazeneca covid vaccine
Oxford-AstraZeneca's vaccine could be given at half-dose initially.
  • The Oxford-AstraZeneca vaccine candidate is 70% effective, on average, according to a press release published on Monday.
  • The vaccine is given as two shots. Efficacy increased to 90% in a smaller group of volunteers who received a half dose in the first shot, then a full dose in the second shot.
  • Experts including Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, are puzzling over the unexpected result.
  • Visit Business Insider's homepage for more stories.

The long-awaited early results from the University of Oxford and AstraZeneca's COVID-19 vaccine trials are in — and experts are puzzling over one big question.

The headline is that the vaccine works. Oxford and AstraZeneca said that the vaccine is 70% effective at protecting against COVID-19.

However, that 70% figure is an average of two efficacy numbers from different tests of the shot, one of which showed the vaccine is 90% effective. Now doctors and scientists are trying to understand how effective the shot really is, and how it stacks up against rival vaccines.

Moderna and Pfizer have both reported that their vaccines are about 95% effective at preventing COVID-19, though each trial measures the figure differently.

The Oxford-AstraZeneca vaccine candidate is given to people as two doses, at least one month apart. The trial data, which comes from late-stage studies in the UK, Brazil and South Africa, suggests that the vaccine is 62% effective if people get two full doses, but 90% effective when they get a half-strength version of the first dose. 

The information was provided in a press release and hasn't been published in a peer-reviewed journal. AstraZeneca and Oxford said they're submitting the results for review and publication.

Britain's William, Duke of Cambridge, wears a mask as he meets scientists during a visit to the manufacturing laboratory where a vaccine against the coronavirus disease (COVID-19) has been produced at the Oxford Vaccine Group's facility at the Churchill Hospital in Oxford, Britain, June 24, 2020. Steve Parsons/Pool via REUTERS
Britain's William, Duke of Cambridge, visits the Oxford Vaccine Group's facility at the Churchill Hospital, in Oxford.

'Digging into the details'

The University of Oxford team doesn't know the exact reason for the differing efficacy figures, but plans to investigate it further, Sarah Gilbert, a professor of vaccinology who leads the Oxford team, said at a press conference on Monday.

"We'll be digging into the details of exactly why we get better efficacy with half-dose, full-dose," she said.

Gilbert said that it may be that the half-dose regimen, "better mimics what happens in a real infection."

"It could be that by giving a small amount of the vaccine to start with and following up with a big amount, that's a better way of kicking the immune system into action and giving us the strongest immune response, and the most effective immune response," she said.

About 2,741 participants in the trial got the half-strength version of the shot first, and all were in the UK, AstraZeneca said.

Dr. Andrew Pollard, director of the Oxford Vaccine Group, said that Oxford scientists originally thought two high doses would cause the best response, and so Pollard said the results are "intriguing." 

Researchers may adjust the US trial to test the half-strength vaccine

Katie Ewer, an associate professor and senior immunologist at the Edward Jenner Institute for Vaccine Research is a key member of the Oxford vaccine team. 

She told Business Insider that it's too late to use these results to make changes to the UK trial. But the researchers may try to test the lower dose strength in the big late-stage study that's currently signing on volunteers in the US, she said.

"They may well decide to look at the low-dose, standard-dose, or they might decide to look at low-dose, low-dose," she said.

Pollard acknowledged that there may be some difference in the effectiveness of the Oxford-AstraZeneca shot and rival vaccines 

But he said it's too soon to say for sure, and he noted that each trial makes different decisions, for example about how to measure efficacy, making it difficult to compare figures from different trials. 

There's likely to be a lot of demand for coronavirus vaccines

Still, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told STAT News that he's worried about who would get each vaccine, should the Oxford-AstraZeneca shot turn out to be less effective.

"If it's 70%, then we've got a dilemma," Fauci said. "Because what are you going to do with the 70% when you've got two [vaccines] that are 95%? Who are you going to give a vaccine like that to?"

Different vaccines have unique characteristics and will likely be used in different places and populations. For example, preliminary results suggest Oxford-AstraZeneca's candidate works best in older adults. It also doesn't need ultra-cold temperatures so it might be the best option for middle and lower income countries who can't afford cold storage, and it's less expensive.

Furthermore, there's likely to be a lot more doses available of the Oxford-AstraZeneca Vaccine than of Moderna's or Pfizer's. AstraZeneca said it plans to be able to make up to 3 billion doses next year.

For now, there will be more than enough demand for any of the vaccines, AstraZeneca CEO Pascal Soriot said on Monday.

"If you add the capacity that Pfizer has announced, plus the Moderna announced capacity, plus our capacity, which is much bigger, the 3 of us don't even have enough vaccine production for the world," he said.

Read the original article on Business Insider