Pedestrians walk past a COVID-19 public health sign in London, on Feb. 25, 2021.Kirsty Wigglesworth/The Associated Press
The head of a British program that tracks variants of the COVID-19 virus says it may have hit “peak fitness” in terms of its ability to spread and evade vaccines.
“We seem to have reached a relative plateau, if you like, of what the virus is doing in terms of evolution,” said Sharon Peacock, director of the COVID-19 Genomics UK consortium, or COG-UK. “It could be that there’s a point at which the virus has kind of optimal fitness in terms of transmissibility and evasion of immunity, and it may be that there will be a pause. What I don’t know is what happens after that.”
COG-UK has been a world leader in sequencing genetic changes to the virus and the consortium, which consists of a network of universities and public health agencies, has sequenced more than 300,000 genomes of the virus.
Dr. Peacock told a news conference on Tuesday that while it was unclear how the virus will continue to evolve, she remained optimistic about the battle to contain COVID-19. “I don’t anticipate that things are necessarily going to get worse,” she said. “Where we see vaccines being rolled out, disease is falling and the vaccines are looking effective. … We’re approaching a period of time when actually the tools and the technology that we’ve developed will come to the fore and help us to combat this virus.”
She made the comments during a briefing on new research into a variant of the virus first detected in Manaus, Brazil, in November. The mutation, known as P1, has spread throughout Brazil and to 25 other countries, including the U.K. and Canada. The P1 variant contains a cluster of mutations that have also been found in the British and South African variants that were also first detected late last year. The mutations help the virus bind to human cells and evade immunity.
COVID-19 is caused by a virus called SARS-CoV-2, and as it spread around the world, it mutated into new forms that are more quickly and easily transmitted through small water droplets in the air. Canadian health officials are most worried about variants that can slip past human immune systems because of a different shape in the spiky protein that latches onto our cells. The bigger fear is that future mutations could be vaccine-resistant, which would make it necessary to tweak existing drugs or develop a new “multivalent” vaccine that works against many types, which could take months or years.
Not all variants are considered equal threats: Only those proven to be more contagious or resistant to physical-distancing measures are considered by the World Health Organization to be “variants of concern.” Five of these been found in Canada so far. The WHO refers to them by a sequence of letters and numbers known as Pango nomenclature, but in May of 2021, it also assigned them Greek letters that experts felt would be easier to remember.
ALPHA (B.1.1.7)
- Country of origin: Britain
- Traits: Pfizer-BioNTech and Moderna vaccines are still mostly effective against it, studies suggest, but for full protection, the booster is essential: With only a first dose, the effectiveness is only about 66 per cent.
- Spread in Canada: First detected in Ontario’s Durham Region in December. It is now Canada’s most common variant type. Every province has had at least one case; Ontario, Quebec and the western provinces have had thousands.
BETA (B.1.351)
- Country of origin: South Africa
- Traits: Some vaccines (including Pfizer’s and Oxford-AstraZeneca’s) appear to be less effective but researchers are still trying to learn more and make sure future versions of their drugs can be modified to fight it.
- Spread in Canada: First case recorded in Mississauga in February. All but a few provinces have had at least one case, but nowhere near as many as B.1.1.7.
GAMMA (P.1)
- Country of origin: Brazil
- Traits: Potentially able to reinfect people who’ve recovered from COVID-19.
- Spread in Canada: B.C. has had hundreds of cases, the largest known concentration of P.1 outside Brazil. More outbreaks have been detected in Ontario and the Prairies.
DELTA (B.1.617 AND B.1.617.2)
- Country of origin: India
- Traits: Spreads more easily. Single-dosed people are less protected against it than those with both vaccine doses.
- Spread in Canada: All but a few provinces have recorded cases, but B.C.’s total has been the largest so far.
LAMBDA (C.37)
- Country of origin: Peru
- Traits: Spreads more easily. Health officials had been monitoring it since last August, but the WHO only designated it a variant of concern in June of 2021.
- Spread in Canada: A handful of travel-related cases were first detected in early July.
If I’m sick, how do I know whether I have a variant?
Health officials need to genetically sequence test samples to see whether it’s the regular virus or a variant, and not everyone’s sample will get screened. It’s safe to assume that, whatever the official variant tallies are in your province, the real numbers are higher. But for your purposes, it doesn’t matter whether you contract a variant or not: Act as though you’re highly contagious, and that you have been since before your symptoms appeared (remember, COVID-19 can be spread asymptomatically). Self-isolate for two weeks. If you have the COVID Alert app, use it to report your test result so others who may have been exposed to you will know to take precautions.
Need more answers? Email audience@globeandmail.com
Researchers from Imperial College London, the University of Cambridge and the University of São Paulo found that the P1 variant was around 50 per cent more transmissible than the original version of the virus. They also concluded that it was able to reinfect between 25 and 61 per cent of people who were already immune to the original virus.
Nuno Faria, a specialist in viral evolution at Imperial College, said he also thought the virus was showing signs of “converging evolution.”
“You do see the same mutations popping up in different parts of the world completely independently and I think that’s something that needs to be taken into account,” Dr. Faria told the briefing. He added that increased tracking of mutations, particularly in developing countries, could still turn up novel variations. “We will see more variants once we increase sequencing in places like the global south. We will probably start seeing far more variants of interest and far more variants of concern.”
Dr. Faria was also hopeful about the fight against the pandemic and the effectiveness of vaccines. “This is a period to be optimistic about the future,” he said. “The more we know about the virus the better we are able to protect against it. There is no concluding evidence to suggest at this point that the current vaccines won’t work against P1.”
Dr. Peacock said that even though the South African and Brazilian variants are highly contagious, they have not outpaced the British mutation in the U.K.
That variant was first detected in November in Kent, southeast of London, and it now accounts for more than 80 per cent of all COVID-19 cases in Britain. Only a handful of cases of the South African and Brazilian variants have emerged in the U.K. and so far they have not spread widely. That has raised questions among scientists about how the different variants behave once they are in the same environment.
“We will learn about the relative fitness of [variants] over time in a given setting but at the moment it’s clear that our lineage is prevailing against the South African variant,” Dr. Peacock said. “I don’t think we should make any assumptions about P1. I think we need to be on our guard, watch and go after this variant.”
A number of recent studies have shown that the Pfizer-BioNTech and Oxford-AstraZeneca vaccines work well against the U.K. variant. A report released this week by Public Health England, which studied 7.5 million people who had been vaccinated, found that both vaccines were highly effective in older people. Data from the agency showed that among people over the age of 80, both vaccines were more than 80 per cent effective in preventing hospitalization three to four weeks after a single dose.
Another study out of Scotland, involving more than one million people who had been vaccinated, found that both vaccines reduced the risk of hospitalization by up to 94 per cent.
The first big real-world study of the Pfizer/BioNTech vaccine to be independently reviewed shows the shot is highly effective at preventing COVID-19, in a potentially landmark moment for countries desperate to end lockdowns and reopen economies.
Reuters
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Paul Waldie