‘We need to double down’: Infectious-disease expert Andrew McArthur on COVID-19 variants

TVO.org speaks with the McMaster University prof about mutations — and what Ontario should do to avoid a third wave with even higher case counts
By Sarah Trick - Published on Feb 01, 2021
Andrew McArthur works at McMaster University’s Michael G. DeGroote Institute for Infectious Disease Research. (Courtesy of Andrew McArthur)



Vaccines and their effectiveness have been the one bright spot during COVID-19. With their arrival, the pandemic shifted from a slog with no end in sight to something that might have an end, if we can just hold on long enough for a mass-vaccination campaign to be put in place.

But the emergence of new and potentially more infectious variants of COVID-19, such as those confirmed in the United Kingdom and South Africa, could throw a wrench in the works. As they’re thought to spread more quickly, there’s concern that we won’t be able to vaccinate effectively enough to get ahead of them.

TVO.org speaks with Andrew McArthur, an associate professor at McMaster University’s Michael G. DeGroote Institute for Infectious Disease Research, about the variants — and what Ontarians need to do to keep themselves and one another safe.

TVO.org: Is it normal for a virus to mutate a lot and give rise to variants?

Andrew McArthur: All organisms mutate over time — with viruses, it’s very common. In fact, we often take advantage of it: the subtle differences mean that we can do the detective work to figure out how the different variants are moving around the planet. So we knew, early on in Ontario, that we were really seeded by people travelling to Florida and on March break.

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Look at influenza: it evolves so quickly that, twice a year, we have to redesign the vaccines for it. COVID-19 actually evolves quite slowly, which is advantageous. The more time that goes by and the more people that are infected, the more likely you're going to get a variant with new properties. And that's exactly the stage we sort of hit around late November, early December with the evolution of the U.K. variant.

TVO.org: When the pandemic started, were you expecting to see different variants, perhaps ones that are more contagious?

McArthur: We were part of the team that sequenced the very first patient in Ontario. We were part of the team that isolated that live virus so you can test vaccines. And the federal government really got this organized in March — we started a couple months before that, and we could see this coming.

So we've been building and doing the surveillance for these viruses all along. From the earliest days, it was really to focus to make sure that diagnostics worked and to design better diagnostics. But always the long-term aim was to look out for variants that would either be more infectious or more deadly or that could possibly reduce the efficiency of the vaccines. Currently, the three variants that we're most concerned about — the U.K., Brazil, and South Africa — are all more infectious. And we know that the South African reduces the efficiency in the vaccine a little bit. Not enough to worry, but it's partway down that path.

TVO.org: So what's really worrisome about these variants?

McArthur: The greatest concern is really the infective aspect. There's no solid evidence that any of these variants are more deadly, though the numbers of deaths in the U.K. were higher than expected, but that could simply be because their health system was overwhelmed. Ontario, in particular, is driving down numbers pretty well, but if the U.K. variant spreads, it is considerably more infectious. So you will see more cases, more people in the hospital, more people in the ICU, and more deaths. It will be harder to contain. That just means that what everyone does to physically distance, wash their hands, stay at home as much as possible — we really need to double down on this until we get herd immunity with mass vaccination.

TVO.org: But do you think that the measures that we're doing right now will be enough to keep numbers down if the U.K. variant does spread here?

McArthur: Yeah, so the Ontario modelling table just announced that, if we relax these measures, we could get a third wave of even higher numbers because of the U.K. variant. I am very concerned that we have pressures to reopen and pressures to reactivate our communities. But this variant makes that considerably harder and harder to control. If we don't do it well, we could lose control again and have a pretty devastating third wave before vaccination really kicks in.

TVO.org: Will these variants keep coming?

McArthur: Yes. It's simply a function of time and the number of patients, so anywhere in the world that's had, you know, a significant number of cases. That's when we do community-level surveillance; it's entirely likely that Ontario could generate its very own variants. Globally, there are labs like mine constantly on the lookout for that.

TVO.org: Even if the vaccines do work for these variants, is there a possibility that there could be more that the vaccines wouldn't be effective against?

McArthur: The drop of the Moderna vaccine from a 90 per cent efficiency to the 70 per cent range for the South African — well, 70 per cent is very good for a vaccine. There's no real concern on generating herd immunity and driving this pandemic off the table. It is entirely conceivable that other mutations in the spike protein could lead to something that could very much more evade the current vaccines.

The key thing is that the vaccines that Canada started with are these new messenger-RNA-based vaccines. These are based on the genetic code, and now that they work and we know how to produce them, we can re-engineer them in under three weeks. So, as new variants are detected from surveillance work, like mine, it is not a big deal for the vaccine companies to retool. We may see a little bit of chase here now that we have a first round of vaccines, and there are variants that escape them. And so we re-engineer the vaccines and do another round. It may take a couple rounds to drive this down. But the technology is a real breakthrough on that quick response to an evolving pathogen.

TVO.org: What do we need to do on an individual level and also on a societal and government level to make sure that more contagious variants don't spread?

McArthur: If we can get the populace to drive numbers down, that gives us the capacity to find these variants and do what's called “search and destroy” — do all the contact tracing and eliminate that train of transmission, eradicate it from our community. The number one thing people can do is drive those numbers down, so we can go back to effective contact tracing where we're not overwhelmed. At an international level, we don't want to be seeded with variants either. That doesn't mean we have to be shut. That means we have to have effective testing and isolation at the border so that we don't introduce these variants to our communities.

TVO.org: Do we need better masks?

McArthur: Yeah, so the U.K. variant, South Africa, Brazil — we're presuming they’re more infective. That means it takes fewer particles from a cough to infect somebody than it did before. So you really want to suppress those particles from a cough spreading to someone: so double masking or wearing a triple-layer mask — not all the way to the N95. Please save those for the health-care workers who need them. The simple cloth mask stops many of the particles but no longer stops enough because of these variants. So additional masking is a good idea.

TVO.org: I remember reading a few weeks ago that people were concerned that the U.K. variant might be more deadly or more severe for children. Is that still a part of the data? And, if so, does that have implications for what we should do about schools?

McArthur: So Prime Minister Boris Johnson did make a statement last week that the U.K. variant is more deadly. Honestly, the data doesn't support that: it's really too early to tell. They had their case numbers got so high that a lot of the mortality has to do with an overwhelmed medical system, not necessarily because of the variant. It's not clear yet if this variant is more deadly for anyone or for any specific group of people.

TVO.org: Has the trajectory of this pandemic been roughly what you thought it was going to be in the beginning, or have there been surprises?

McArthur: There are parts that certainly were expected, and there are parts that were an extraordinary surprise. Unfortunately, we expected the second wave. There has never really been a pandemic in history without a bigger second wave. And the second wave has to do with pandemic fatigue and having Thanksgiving and Christmas. So we knew that was coming. I think the first wave, I was just thrilled at how well everybody did and how well they fought it: Australia and Canada effectively eliminated the flu season, and that is a marker of just how good a job people did.

But a virus that has a capacity to change in how it moves around, and in its infectivity, it's messed with the diagnostics so you've had to redesign them. It's certainly been a running target.

I was really pleased early on when work out of Sunnybrook [Health Sciences Centre, in Toronto] and McMaster showed that it did not mess with the immune system like HIV does. That was a good day to know that this virus was not going to interfere with the immune system, which keeps the door open for vaccines. I think the greatest surprise was the success of the mRNA vaccines. They've been under development for so long to fight cancer and other things. And this was their moment: 10 years of hard work to make sure that they were safe and efficient just came to fruition at the right time. To have mass production so quickly is really remarkable.

TVO.org: So where is your research going next?

McArthur: Our real bigger research concern is antimicrobial resistance, drug-resistant infections. And, unfortunately, when you treat a coronavirus patient in the ICU, you'll have to use a lot of antibiotics to keep secondary infections under control — and that breeds superbugs.

As researchers, we’re already preparing for a wave of drug-resistant lung infections once we defeat this coronavirus. Antimicrobial resistance (AMR) is already pretty devastating; we lose drugs at a high frequency. Modern medicine is under threat from AMR, and this is going to exacerbate it. We're fighting a pathogen that we had no therapeutics for. So we have no choice but to use the antibiotics to save the patient — I'm not going to argue that; it has to be done. But there will be blowback, and there are going to be some really difficult problems after this. As researchers, we're preparing for that. As epidemiologists, we're all in on the day-to-day work of tracking patients, trying to find these variants, and trying to help our clinicians make better decisions.

TVO.org: Is there anything else that you think our readers should know?

McArthur: The toughest thing now is that it's we're all tired of doing this, and the vaccines give such a glimmer of hope. And we're eager for that day. But, in some ways, we are in one of the most dangerous stages of the pandemic, in that enough time has gone by — and enough infections — that these variants are going to occur. And there will be more, and we could generate our own. Vigilance and rolling up the sleeves and doing everything you can to reduce the transmission rates and get those numbers down buys everyone time, will save lives, and will allow the vaccines to do their job.

This interview has been condensed and edited for length and clarity.

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