With COVID-19 restrictions lifting across the country, Canadians may be feeling as though aspects of their lives are starting to return to “normal.” But experts warn that ending long-standing practices such as physical distancing and masking will not only increase transmission, but raise the chances that a new COVID-19 variant will emerge.
“Every person that the virus infects, that’s a lottery ticket for that virus to up its chances of being able to generate a new variant that’s better [and] nastier than the previous variant,” infectious disease expert Matthew Miller told CTVNews.ca in a phone interview on Wednesday. “By virtue of the fact that we are not infected, we’re giving the virus less chance to mutate.”
As a virus replicates, it develops mutations in the hopes of becoming more infectious and increasing its spread, therefore improving its ability to survive, said Miller, an associate professor at McMaster University’s Michael G. DeGroote Institute for Infectious Disease Research based in Hamilton. This is what leads to the emergence of new variants. By spreading to more people, this provides the virus with more opportunities to mutate, Miller said.
The concept of viruses replicating and modifying their genetic makeup based on selective pressures is a normal part of the virus lifecycle, said Dr. Sumon Chakrabarti, an infectious diseases physician with Trillium Health Partners in Mississauga, Ont.
“People have to understand that viruses have been varianting [sic] forever, and we don’t control that,” Chakrabarti told CTVNews.ca on Wednesday in a phone interview. “Variants will continue to come as a natural part of viral evolution.”
Still, as more people become infected with SARS-CoV-2, chances are COVID-19 variants will appear at a much faster pace, said Miller. The removal of COVID-19 restrictions will undoubtedly lead to an increase in the spread of the virus, Miller said, which will also increase the likelihood that new variants will soon emerge.
“There’s no question that lifting restrictions is going to lead to higher rates of transmission,” said Miller. “Anytime you get rid of a public health measure, you give the virus a better chance of transmitting.”
It’s also important to consider the role that vaccination plays in the surfacing of new COVID-19 variants, said Dr. Brian Conway, an infectious disease expert and medical director of the Vancouver Infectious Diseases Centre. The fewer people that are fully vaccinated against COVID-19, the greater the potential for a new variant to not only emerge, but to spread, said Conway. With about 43 per cent of the world not yet vaccinated with at least two doses, this leaves about three billion people highly susceptible to being infected with COVID-19, he said.
“Variants are dependent on the virus replicating in real life, so the more susceptible hosts you have, the more virus you will have [circulating],” he said. “Since it replicates so much, just by randomness, it will develop some new variants that will survive.”
But it’s also important to remember that vaccination is only somewhat efficient at protecting against infection, particularly when caused by the predominant Omicron variant. A recent study conducted in England between November 2021 and January 2022 revealed that the efficacy of two Pfizer vaccine doses against symptomatic disease brought about by Omicron was 65.5 per cent after two to four weeks, before falling to 8.8 per cent 25 or more weeks after vaccination.
With a booster dose of the Pfizer vaccine, protection increased to 67.2 per cent after two to four weeks, but also began to wane as more time went on. At 10 weeks post-vaccination, three doses of the vaccine were only 45.7 per cent effective against symptomatic COVID-19 illness.
Because of this, public health measures also play a critical role in protecting against infection, Miller said. This includes wearing a well-fitted mask in crowded settings and maintaining two metres’ distance from others when possible. He also recommends that people maintain diligent hand hygiene and keep a distance from those who are suspected of being sick. These measures will not only help to curb the transmission of COVID-19, but also decrease the speed at which new variants may appear, Miller said.
“Anything that is risk-reducing slows down this rate of variants emerging,” said Miller. “We have to layer other preventative measures on top of [vaccines].”
WHAT COULD A NEW COVID-19 VARIANT LOOK LIKE?
According to Conway, the emergence of new COVID-19 variants is inevitable so long as the virus is able to spread and survive. In terms of what future variants of COVID-19 could look like, it is possible that they will continue to be milder and highly transmissible among the general population, he said, similar to the Omicron variant that has displaced Delta in Canada.
With such a strong pressure to survive and transmit, Miller said, some of the characteristics associated with increased transmissibility are also tied to reduced severity of disease. With Omicron, for example, research shows that the virus mainly causes infection in the upper respiratory tract, such as the throat area, as it appears to replicate faster in airway passages as opposed to inside lung tissues.
“The throat is just physically closer to your mouth and nose, and if you’ve got more virus up there, it’s easier for that virus to get out and get to the next person,” said Miller. “If the virus is deep down in your lungs, it has to travel a lot further to get out and transmit.
“That kind of thing can help to reduce the severity [since] infections that are deep in your lungs also happen to have the consequence of making you much more sick.”
It is possible for future variants to follow a similar trend, said Chakrabarti.
“[Viruses] tend to push towards something that is transmitted very easily and oftentimes, killing the host is something that would hinder that,” he said. “Not every virus follows this route…but that tends to be the feeling.”
Miller also pointed out that historically, as pandemics have evolved, viruses would eventually cause milder disease due to widespread immunity that was developed over time, which would mitigate the severity of infection.
“Everyone having been vaccinated and many people having been some combination of vaccinated and infected…means that the level of immunity that we have against the virus is continuing to increase,” said Miller. “Those immune responses are going to protect us much better [from severe disease] than they did early in the pandemic when our immune system really didn’t know what COVID was at all.”
Still, the idea that future COVID-19 variants will continue to be mild and increasingly transmissible is not guaranteed, Miller said, and it’s important for the world to be prepared for a new variant that could instead be more dangerous than anything seen before.
“We have to be ready for the possibility that there could be a variant that arises and is worse than what we see with Omicron,” he said. “It’s certainly not impossible given the pressures that are driving the virus to mutate and for these new variants to emerge.”
COVID-19 HERD IMMUNITY REMAINS UNLIKELY
Its ability to mutate so frequently is one of the main reasons why herd immunity remains difficult to achieve with SARS-CoV-2, the virus that causes COVID-19, said Chakrabarti. Herd immunity is when enough people become immune to a pathogen, either through vaccination, exposure to infection or both, and consequently protect a smaller number of those remaining people who are more vulnerable to getting infected, said Conway.
“If the virus were to be present in that community, there aren’t enough people around who are susceptible to infection to sustain the spread,” he said. “So the herd or the community would be immune to that particular virus.
While herd immunity has been successfully achieved with other diseases, it’s not as easy to attain with COVID-19, Miller said. Additionally, with the newest variant of concern capable of evading some of the immune responses developed by the body, this makes the chances of building a strong herd immunity response unlikely, he said.
“I don’t think that we will ever get to that extreme end of herd immunity with SARS-CoV-2 that we’ve seen for other pathogens like smallpox, polio and arguably in a lot of settings, measles,” said Miller. “We’re likely to see a situation where this virus becomes endemic and we’re unlikely to be able to eliminate it altogether.”
Conway also pointed to evidence of waning immunity from current COVID-19 vaccines. Studies have shown that vaccine protection appears to wane as early as a few months after they are administered.
“We’re realizing that the immunity from the vaccine wears off after several months, and it wears off at different rates in different people,” said Conway. “So the community can’t be protected at a high level for an extended period of time.”
It’s also important to consider the role of transmission, said Chakrabarti. For herd immunity to occur, there must be low levels of viral transmission, which have not yet been achieved, he said.
“We’re not quite there; you can see that we get these big waves [of cases] and they go down for a bit, then another wave,” said Chakrabarti. “Based on what we know of the virus and its immune evasion…[transmission] is not in that low-level, long-term equilibrium.”
Targeted vaccines developed specifically for COVID-19 variants as they emerge might make herd immunity a possibility in the future, provided they offer better overall protection than current vaccines, said Miller. Pharmaceutical companies such as Pfizer and Moderna have each announced plans to develop Omicron-specific vaccines. These plans, however, have since been delayed, with both companies still gathering data on the efficacy of these jabs.
“When we get vaccines that are a better match for the [variant] that’s currently circulating, the effectiveness of those vaccines will also increase,” said Miller. “Updating vaccines and having vaccines that are capable of conferring broader immunity against variants will increase the strength of this indirect protection.”
But it appears as though there may be some time until these vaccines are developed and rolled out, with Moderna now aiming for August, for example. This makes additional COVID-19 protective measures such as masking and physical distancing even more important in curbing the spread of the virus as well as preventing future variants that may emerge, Miller said.
“It’s like adding an extra layer of armour essentially,” said Miller. “When we start combining interventions, that makes it harder for the virus to transmit and essentially, anything that makes it harder for the virus to transmit helps us to reduce its circulation and provide that indirect protection to people who are susceptible to getting ill.”
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