A new genetic variant of COVID-19 surfacing in Britain made headlines earlier this week, with many outlets reporting that it could be 70 per cent more transmissible than the current predominant strain.
With the United Kingdom heading into a lockdown and scientists sharing the preliminary facts, the Canadian government announced on Sunday, Dec. 20, 2020 a decision to suspend flights from the UK for 72 hours, in step with several other countries. Canada extended the ban yesterday until Wednesday, Jan. 6, 2020.
“Genetic variation of viruses such as the one that causes COVID-19 is to be expected and have been previously observed in parts of the world this year,” said a statement from the Public Health Agency in Canada on Sunday. “While early data suggest that the United Kingdom variant may be more transmissible, to date there is no evidence that the mutations have any impact on symptom severity, antibody response or vaccine efficacy.”
Dr. Gerald Evans, an infectious disease specialist at Kingston Health Sciences Centre (KHSC) and Professor at Queen’s University School of Medicine says there’s still much more unknown than known about the new strain of COVID-19. He is skeptical about the way the story has hit newsstands.
“The initial discussion point was brought forward by a politician in the UK,” Dr. Evans said on Tuesday, Dec. 22, 2020. “They brought it up as one of the reasons why they were going into the lockdown in Britain. Whenever a politician says something, the media picks it up like crazy. Much more so than if it was a scientist, unless it’s Tony Fauci or someone like that. That’s the reason why it’s taken off.”
Understanding the ‘R number’
As of Tuesday, Dr. Evans said two initial observations were being used to label the virus more transmissible, which could both be false.
“It would appear that in areas where that variant has been seen in larger numbers, the reproductive number looks a little bit higher,” he said.
The reproductive, or R number, indicates the number of people a single infected person is expected to pass the virus to within a susceptible population. It depends on several variables including population density, peoples’ adherence to public health measures, contact tracing capacity, and the properties of the virus itself.
“It was thought to be anywhere from a 0.4 to 0.9 higher R number. So … in an area where the reproductive number was 2, it will raise it up to 2.4 or 2.9. But that is based on information that is derived from counting the effective R number in an area where the virus is highly prevalent,” he said. “There are a whole bunch of other reasons why the reproductive number could be elevated, and it has nothing to do with that variant strain.”
If for instance, he said, people in London, where the strain emerged, were taking a relaxed approach to social distancing then the effective R number would go up. Having multiple venues open to allow for transmission could have the same effect.
“You might draw the conclusion that it’s the virus when in fact it’s just people not doing what they should do,” he said.
Dr. Evans noted that the strain of the virus observed in Britain — N501Y — is not unique to that country, and had already been seen in South Africa and other locations.
It’s also not the first time COVID-19 mutation has been labelled “more transmissible,” at first, and then later found not to be. “Way back in the spring D614G was described as being more transmissible but in fact it did not appear to be the case,” he said.
Cycle Threshold (Ct)
The second observation raising questions about the transmissibility of the new strain of COVID-19 is its cycle threshold (Ct), he said, which refers to the number of cycles of a PCR test required to detect the viral RNA.
“If the cycle threshold is low, it means you only have to run the PCR test through fewer cycles and you can detect COVID-19. So a low Ct means more virus. They’re saying: if there’s more virus then those people are going to be ‘shedding’ it more, and it’s going to infect more people,” Dr. Evans said.
With such limited evidence to suggest higher transmissibility, he suggested the enthusiastic media response to the story made it easier for the British government to justify lockdown measures, imposed on Britons heading into Christmas.
“Instead of saying ‘Oh no, we made a mistake, we should have left the lockdown in longer and we eased it off too soon,’ they can say ‘Well actually, mostly we [imposed] the lockdown because there’s this more transmissible virus,’” he said.
Answering tough questions
Dr. Evans said there are three questions that need to be answered to assess the risk associated with the new strain of COVID-19:
- Does it increase infectability or transmissibility?
- Does it increase the severity of the disease (is it more virulent)?
- Does it affect the effectiveness of the vaccine that we’re currently rolling out?
“The only thing I’ve heard talk about is the transmissibility and that’s a bit confusing right now,” he said Tuesday. “They’re going to have to do much more careful analysis in many different parts of the world with the same mutation of the virus to determine is this in fact a transmissibility issue.”
“Virulence is tough,” he added. “That would mean looking at a whole group of people who had this particular infection, and then comparing them to people who don’t have that infection and controlling for things like: How old were the people? Were they male or female? Etc. That, we’re far away from.”
He said determining the vaccine question is simple. “The vaccine issue is probably relatively easy to sort out. We take the antibodies that are developed by the vaccine … We put that in a cell culture, and put the variant virus in with it and ask: Did it block the virus from being able to enter the cells that I have in the cell culture?”
The CEO of BioNTech, Ugur Sahin, as well as UK Prime Minister Boris Johnson have both publicly stated this week that the virus is likely to respond to current vaccines, though investigation is ongoing.
On Wednesday, Dec. 23, 2020, British Health secretary Matt Hancock confirmed that scientists had identified yet another variation in two travellers from South Africa. As a result, Britain has now halted flights from that country while research continues.