All viruses mutate, it’s just what they do.
Scientists create a new flu vaccine every year, for instance, just to keep up.
For SARS-CoV-2, the virus that causes COVID-19, the idea of a mutation is inherently scary for many people, but experts insist it’s to be expected.
What that might mean for vaccine effectiveness? At this point, not much, experts say.
“I don’t want people saying, ‘I’m going to wait for my vaccine because I heard about this one mutation in England,'” said Dr. Gerald Evans, chair of infectious diseases division at Queen’s University in Kingston, Ont.
“We don’t know if it’s going to change anything. I don’t suspect it will — most mutations don’t — but time will tell.”
So far, there have been few variants of the new novel coronavirus — fewer than experts expected, in fact. The good news is that those variants have so far not been meaningful enough to affect the virus’s behaviour or the vaccine’s ability to ward it off.
But any new mutation “bears a little bit of watching,” said Evans, including the recent discovery in the U.K.
British scientists are trying to establish whether a surge of cases in southern England is associated with a new “variant” of COVID-19. At this point, there’s no evidence to suggest these mutations make the virus any more deadly, more transmittable, or capable of rendering the vaccine useless.
But some experts say the types of these new mutations are noteworthy.
Both mutations — “N501” and “H69/V70 deletion” — are found in the spike protein, which allows the coronavirus to infiltrate and hijack our body’s cells. It could, in theory, result in COVID-19 spreading more easily between people.
H69/V70 deletion is not a new mutation for COVID-19 — it’s the same mutation that famously infected mink in Denmark. The concern here was that antibodies from the blood of those who recovered from COVID-19 were less effective at attacking that variant of the virus.
N501, meanwhile, alters an important part of the spike known as the “receptor-binding domain,” which might make it easier for the virus to get inside.
“That’s important because when we’re looking at neutralizing antibodies — that is antibodies that protect you from infection — there are some specifically directed at that spike protein, and in some cases, specifically to that receptor-binding domain. So when you make an antibody, it sort of blocks that area from attaching to you,” said Evans, who also sits on the COVID-19 advisory council for Ontario.
“We think that’s the main vaccine strategy for preventing the virus from infecting you, but it’s too early to know if it’s going to cause any problems.”
So, will mutations affect vaccines?
While not impossible, mutations affecting the efficacy of vaccines is doubtful, according to Levon Abrahamyan, a virologist at the University of Montreal.
Coronaviruses are genetically stable, he said, which means they mutate very slowly. Some experts estimate that the coronavirus accumulates about two mutations per month, which is considered to be about half the rate estimated for influenza.
Essentially, in order to evade immunity, a virus is forced to change or replicate. When a virus tries to replicate, it collects errors or mistakes over time, according to Abrahamyan. These mistakes — i.e. accidental changes in its RNA — can become variants or mutations.
They are less common in coronavirus than influenza, in part because of its proteins.
COVID-19 proteins can essentially “proofread” which, in theory, means that it corrects mutations as they happen, therefore reducing the number of possible mutations. The flu virus does not have this built-in mechanism.
That’s good news where a vaccine is concerned, experts agree.
So far, the genetic evidence about SARS-CoV-2 suggests that the frontrunner vaccines — Pfizer, Moderna, Oxford-AstraZeneca — are unlikely to need much modification in the future because of the virus’ relatively stable genome.
In other words, the original vaccine created to target COVID-19 should work in the long-run, said Abrahamyan.
“The frequency of mutations in influenza is much, much higher than this new coronavirus,” he said. “I don’t see a real danger to our vaccine development.”
Even then, new technology can back it up.
The introduction of mRNA or messenger RNA technology into vaccine development was “revolutionary” to the success of the vaccines we see now, said Isaac Bogoch, an infectious disease expert based out of Toronto General Hospital.
The technology proved to be more potent and straightforward for Moderna Inc., which attributes its rapidly designed sequence for the vaccine to the technology.
This same technology will help tackle any mutations discovered now or in the future, he said.
“If there was a change to COVID-19, we could use the exact same technology to produce a new vaccine or modify existing platforms for vaccination,” he said.
Abrahamyan suggested a tweak for a mutation could be even quicker — “maybe one or two days.”
It’s important to remember that “most mutations do nothing,” said Bogoch.
The majority of the mutations seen so far have had no apparent effect on the virus, and only a minority are likely to change the virus in any significant way — for example, making it more able to infect people, more likely to cause severe illness, or less sensitive to natural or vaccine-induced immune defenses.
They don’t tend to have a significant change to how this virus interacts with us, Bogoch added, but it’s still important to “not sweep this under the rug.”
“While we don’t have all the information yet, these are answerable questions,” he said. “We have the appropriate expertise to address them, and they’re doing so.”
Rigorous analysis and experiments in a laboratory setting will be required to find out if these variants are more infectious or spread better than others. That’s already underway in the U.K.
In the meantime, there’s no reason to panic, the experts agree.
“The virus is doing what viruses do,” said Evans.
–With files from Reuters and the Associated PressView link »