COVID variants: Evolution at work

Question: Why are the new variants of the coronavirus so contagious and how can I protect myself from them?

Answer: The first thing you need to know is that the emergence of new variants is a normal and expected development.

It’s a process that happens when the virus commandeers the molecular machinery of an infected human cell to replicate itself. Tiny copying errors, or mutations, occasionally occur as 30,000 letters of RNA are assembled to reproduce the genetic code of the virus. 

Many of these random changes have no discernable effect or may even be detrimental to the virus. But a few of them will provide some type of competitive advantage.

“This is evolution at work,” explains Peter Jüni, scientific director of Ontario’s COVID-19 Scientific Advisory Table. The mutations that increase the chances of a new variant spreading tend to keep getting passed along. 

Scientists are still trying to determine how the latest variants differ from the original version of SARS-CoV-2, the official name of the coronavirus that causes COVID-19.

Jüni says the worrisome variants that were first detected in the United Kingdom, South Africa, and Brazil all have mutations in the genes that produce spike proteins, the knobby protrusions that the virus uses to latch onto receptors on the surfaces of certain human cells.

He says he thinks these mutations enable the spike proteins “to fit more snugly” and create a “tighter fit” on the receptor, making the virus more likely to enter a human cell. This could mean “a low dose of the virus might be enough to infect the body.”

Each one of the variants may contain additional mutations that boost their odds of survival and propagation. The South African variant appears to have some ability to evade the immune system’s antibodies, which makes certain vaccines less effective against it.

 Overall, the new variants are roughly 40 per cent more transmissible than the original SARS-CoV-2.

“More mutations are coming – that’s natural. But this is not a reason to panic,” says Jüni, who is also a professor of medicine and epidemiology at the University of Toronto.

“We have new technology that will make it much easier to alter, or tweak, vaccines as new variants emerge.” For instance, messenger-RNA vaccines, which use synthetic raw materials, can be produced faster than some traditional vaccines, like flu shots that rely on viral samples grown in eggs.    

Even more important, people can protect themselves from infection by adhering to well-established precautionary measures such as mask wearing, frequent handwashing and physical distancing – keeping at least two metres apart. On top of these things, people can stay safe by avoiding gatherings in poorly ventilated indoor spaces. 

“I know it sounds like a broken record but we just need to follow the same guidelines that we have been,” says Rob Kozak, a scientist and clinical microbiologist at Sunnybrook Health Sciences Centre in Toronto. “The virus can’t hibernate or hide somewhere. It only exists if it keeps being transmitted to new hosts.

“So, we can stop it if we don’t become complacent and let down our guard.”

In the case of masks, they don’t necessarily need to be medical grade. A three-layered fabric mask – which might include a disposable or washable filter – can block the transmission of the virus.

However, to be truly effective,  a mask must be worn correctly – covering the nose and mouth with no gaps around the edges.

Anthony Fauci, the leading infectious diseases physician in the United States, has publicly speculated that two masks might be better than one. And others have suggested that putting a tight mask on top of a high-quality mask could create a snugger fit to enhance protection and minimize the leakage of the tiny viral particles.

But many Canadian experts are still reluctant to embrace the idea of double-masking.

Janine McCready, an infectious diseases physician at Michael Garron Hospital in Toronto, says some people might find that wearing two masks is hot and uncomfortable. “You may be touching your face more often to adjust the masks,” she adds. And, if you have picked up the virus on your hands, this could lead to self-contamination. 

People might consider doubling up if they can’t find a good mask that fits, says McCready. But she suggests they should first explore some creative solutions. That could mean knotting the ear loops to make them shorter or using a clip to pull the loops together at the back of the head in order to tighten the seal around the face. 

Although experts generally agree that basic safety procedures can block transmission of the virus, certain public health measures may need to be revised to deal with the new and highly contagious variants.

McCready points out that some public-health units have been using 15 minutes of exposure as a key measurement in their contact-tracing efforts.  In particular, people who have been exposed to an infected individual for at least 15 minutes are urged to get tested and self-isolate until they are given the all-clear.

“If you need less exposure to actually get sick from the virus, then  maybe we should change the 15-minute threshold,” she says. “It is probably better to test and isolate more people to make sure we are controlling the spread.”

Even with such adjustments, the new variants are still going to increase the risk that people will become infected. “You can’t really expect that people are always going to be perfect in their adherence to safety measures,” says McCready. 

To prevent the healthcare system from being overwhelmed with COVID-19 patients, additional government interventions may be necessary to limit the number of new cases, says Andrew Morris, an infectious diseases specialist at Sinai Health and the University Health Network in Toronto.  

“Providing paid sick leave is one way to reduce the rate of transmission,” says Morris. Simply put, infected essential workers can then afford to stay home so they don’t pass the illness on to others. 

“These variants are concerning,” says Morris. “But we now know enough to be able to control them quite well. We just have to be smart about what we do.”

Of course, much will change when vaccinations ramp up across Canada. Kozak sees reasons for optimism despite the possibility that some vaccines might not provide the same level of protection against certain variants.

“I think it is important for everyone to remember that with all the vaccine trial data – even in regions where variants are circulating – we haven’t seen anyone who is vaccinated dying from COVID-19,” he says.

So, in terms of the most critical measurement – preventing deaths – all the vaccines appear to be effective.

The comments section is closed.


Paul Taylor


Paul Taylor is a health journalist and former Patient Navigation Advisor at Sunnybrook Health Sciences Centre, where he provided advice and answered questions from patients and their families. Paul will continue to write occasional columns for Healthy Debate.

Republish this article

Republish this article on your website under the creative commons licence.

Learn more