The SARS-CoV-2 virus (novel coronavirus) keeps mutating, bringing new complications in the fight against the COVID-19 pandemic. But although new variants will keep cropping up, experts say we shouldn’t worry too much yet, as mutations are expected in viruses, and so far, the vaccines still seem effective against them.
“The good news is so far the vaccines work against the Delta variant,” said Dr. Maria Van Kerkhove, an infectious disease epidemiologist with the World Health Organization, at a press conference Monday.
“But there may be a time when we have a constellation of mutations that arise in a variant where our vaccines actually lose their potency.”
So far though, evidence from Public Health England shows that two shots of the Pfizer or AstraZeneca vaccine are good at preventing severe illness from the Delta variant.
But the mutations keep coming.
The latest viral mutation to make headlines is the “Delta plus” variant, which India has named a variant of concern due to the possibility that it transmits more easily. It’s a sub-lineage of the Delta variant, which has been gaining a foothold worldwide.
According to a report from Reuters, at least one case of the new mutation has been identified in Canada, though the WHO says that it does not appear to be common around the world.
Little is currently known about Delta plus, but studies are ongoing in India and globally to test the effectiveness of vaccines against this mutation.
Why viruses mutate
Mutation is an expected part of virus life, according to Alyson Kelvin, a vaccinologist with the Vaccine and Infectious Disease Organization at the University of Saskatchewan.
“Viruses mutate. It’s something that happens,” she said. “They infect our cells and when they do this, they replicate their genomes — the information that kind of plans what the virus is going to look like. And as it’s replicating, mistakes happen.”
Some of these mistakes make no difference at all, she said, but those mutations that survive to be passed on to the next generation might give some kind of advantage to the virus, whether that’s helping it spread more easily between people, infect cells more readily, or survive better inside our bodies.
“We’re seeing variants emerge all the time,” said Jason Kindrachuk, an assistant professor and Canada Research Chair in Emerging Viruses at the University of Manitoba. “Literally from person to person as those changes are being made, we’re seeing new variants.”
Why we're seeing more mutations
Variants do seem to be on the upswing, though. Partly, this might be because health authorities are keeping better track of variants now than they were at the beginning of the pandemic, Kelvin said, but it’s also due to the size of the pandemic.
“Each time somebody is infected, that’s an opportunity for a new mutation to happen. So perhaps there are more mutations just because we have more people being infected, that gives more opportunity,” she said.
This points to the importance of fighting the virus worldwide, Kindrachuk said.
“Until we get control of transmission across the globe, what’s going to happen is we continue to open up the opportunity for this virus to change and to be able to adapt,” he said. “And that really is a concern for us. It’s a concern for those communities that are being affected. But we also have to think about the fact that ultimately they will have an effect on us as well.”
And while vaccinating people helps to reduce the number of chances the virus has to mutate, he said, having a lot of partially vaccinated people around could mean that virus strains that do survive are more likely to be able to at least somewhat evade the immunity generated by the vaccines.
“They will change over time just based on that idea of fitness and being presented with something new,” he said. “So when we think about vaccines and partial immunity, it certainly has been a concern for us that, listen, if we see broad partial immunity in communities, will that drive some of this fitness? It could, but it will likely take quite a bit of time to do that.”
Kelvin notes that the SARS-CoV-2 virus doesn’t mutate as quickly as the influenza virus or HIV, which means that it’s probably less likely to completely escape vaccines, or it will take many more mutations to get there.
“At this point, we don’t know if pre-existing immunity or vaccine-induced immunity will drive new mutations and new variants,” she said. “When we look at different viruses and escape from pre-existing immunity or vaccine-induced immunity, really, the only example of a virus doing this is the influenza virus, and that’s because it has a higher level of mutation.”
Vaccinating as many people as possible is still key though, she said.
“We definitely will continue to see variants come up. What’s important is that we’re continuing to be vaccinated to reach herd immunity, which will decrease the virus’s opportunity to mutate. So the more people that have this level of immunity, the less opportunity the virus will have to mutate and the fewer variants we’ll see in the future.”
The best way to prevent mutations that allow the virus to evade vaccines is by preventing infections in the first place, Van Kerkhove said.
“Vaccines are incredibly powerful, but we have other tools as well. Do what you can around the world if you’re listening to prevent yourself from getting infected and to take all the measures that you can to prevent any onward spread should you be infected.”