Are coronavirus mutations a bad sign? Here’s what scientists say
Viruses and mutations go together like peanut butter and jelly.
These minute changes in a virus’s genetic material happen all the time as they replicate and spread around the world, much like what the new coronavirus is doing today.
The term “mutation” often has a negative connotation, but the action it carries helps scientists study where a pathogen came from and how its been spreading, ultimately teaching experts how to contain it.
“As soon as the word ‘mutation’ comes into the story it means that something grand has happened, either for the better or worse,” Nathan Grubaugh, a virologist at the Yale School of Public Health in New Haven, Connecticut, told Popular Science. “And that’s just not the way that evolution works. We all have mutations. We all are genetically different from our ancestors.”
A group of researchers from China said the coronavirus has already mutated into more than 30 different strains, or versions, according to their study published Sunday in the preprint server medRxiv, a site for non peer-reviewed scientific papers.
The study also said that one of the new coronavirus strains has developed 270-times the viral load, providing “direct evidence that the SARS-CoV-2 has acquired mutations capable of substantially changing its pathogenicity,” the preprint said.
In other words, some versions of the virus have become much more deadly, the researchers said.
But other scientists disagree. Here’s why.
What are mutations?
Mutations are changes in the virus’s genetic information that bring about “diversity among organisms,” a library of information by Nature said.
They are also the reason why the new coronavirus hopped from one unidentified animal to people in the market in Wuhan, Hubei Province in China, where the outbreak began, Business Insider reported.
“If you follow a transmission chain in which one person with flu infects another person and they infect another person and so on, you’ll find that the virus mutates about once every 10 days across its genome,” according to a Twitter thread posted by Trevor Bedford, an associate member at the Fred Hutch in the vaccine and infectious disease division and the computational biology program.
Why do mutations happen?
The genetic material, or genome, of the new coronavirus is made up of RNA, which stands for ribonucleic acid. RNA helps the body produce proteins, among other functions, and is known to have a fast mutation rate.
This is because RNA lacks a proofreading function that viruses made up of DNA have, scientists have learned. This proofreader helps catch errors, or mutations, made during replication.
Some mutations help viruses spread quicker or infect a new host, anything that can help it survive in the environment they live in, according to a 2018 paper in the journal PLOS Biology.
“There’s no need for the [new coronavirus] to diversify —it’s spreading incredibly well between humans, and not under a lot of selection pressure to change,” Emma Hodcroft, a geneticist at the University of Basel in Switzerland, told Business Insider. “The virus already has asymptomatic transmission, there’s nothing more it could do to get even more off the testing radar than it already has.”
How fast do mutations occur?
The good news is that the new coronavirus is mutating slowly, Live Science reported.
“SARS-CoV-2 seems to have a mutation rate of less than 25 mutations per year, whereas the seasonal flu has a mutation rate of almost 50 mutations per year,” the outlet said.
“Even if we take the two most different novel coronavirus strains, we find that they’re separated by about 40 differences over the course of 29,000,” Hodcroft told Business Insider. “So people shouldn’t worry about it mutating out of control.”
But it’s important to note that if enough of these changes occur for them to mean something, it will take years for that to happen, Bedford said on Twitter.
Are mutations bad?
The short answer is no.
“Almost all of these mutations will have little to no effect on virus function,” Bedford said. “Evolution weeds out the mutations that ‘break’ the virus and mutations that make a virus replicate better are extremely rare.”
How contagious a virus is or harmful it is to its host depends on multiple genes within a genome, and changing them is a “complicated process, and not often the work of a single mutation,” Popular Science reported.
Even then, the majority of mutations that do occur either do not change how the pathogen functions, or hurt the virus in a way that blocks its ability to survive or replicate, Grubaugh added.
“So the odds of the virus mutating in such a way that it actually becomes more lethal or contagious over the timescale of weeks, months, or even a couple years aren’t very high,” the outlet said.
Do mutations hurt vaccine development?
On the contrary, the slow mutation rate of the virus can help vaccine development, experts say.
This is a good sign because that means a future vaccine can “remain effective for a long time,” Hodcroft told Business Insider.
The 2009 H1N1 pandemic, better known as the swine flu, took three years before there was any evidence of genetic mutations, Bedford said on Twitter.
“If I had to guess, I would predict that #SARSCoV2 will behave similarly to existing seasonal coronaviruses in its ability to mutate to avoid vaccines and immunity,” he said. “So, my prediction is that we should see occasional mutations to the spike protein of #SARSCoV2 that allow the virus to partially escape from vaccines or existing ‘herd’ immunity, but that this process will most likely take years rather than months.”
But it’s possible that the new coronavirus, if seasonal like the flu, can mutate after a vaccine has already been developed, which is why the World Health Organization has to update the influenza vaccine every year, Bedford said.
This story was originally published April 24, 2020 at 10:04 AM with the headline "Are coronavirus mutations a bad sign? Here’s what scientists say."
