Yes, the novel coronavirus mutates. Possibly fast.
No, that doesn’t necessarily make the virus deadlier. Instead, there’s another—and equally chilling—possible explanation for the high death rate associated with COVID-19.
It could be that our own genes, rather than the virus’s, largely account for the wide range of outcomes when people are infected by SARS-CoV-2.
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That’s the consensus from a panel of scientists The Daily Beast spoke to in order to understand how SARS-CoV-2 evolves over time and distance as it spreads across the planet.
“We have lots of samples collected at various times and, with the exception of technical errors, we can then see exactly what has happened through time,” David Morrison, a biologist at Uppsala University in Sweden, told The Daily Beast.
And what has happened is that the novel coronavirus has evolved. Seemingly very quickly at times.
Analyzing pathogen genomes from the GISAID global database, a team of U.K. scientists led by Cambridge University geneticist Peter Forster traced the early months of the novel coronavirus’ spread across Asia, Europe and the Americas.
The team concluded that, by early March, there were three major strains of the virus, each with its own home territory. And mutations undoubtedly continued through March and April.
“We can be quite confident of the viral mutations and mutation rates,” Forster said, “because new genome sequences are added every week, and so we can see the number of mutations increasing on average month by month.”
Morrison pointed to the case of Diamond Princess, a cruise ship that suffered an outbreak of the novel coronavirus while docked in Hong Kong in early February.
The ship sailed to Japan, where authorities quarantined it and all 3,711 people aboard. Over the next month, more than 700 passengers and crew caught SARS-CoV-2. Most got sick. Seven died.
As the novel coronavirus raced through the vessel, jumping from person to person, it mutated fast, ultimately producing variants of the virus that scientists would never see anywhere else.
“To me, this seems like quite a high mutation rate,” Morrison said.
Emphasis on seems. There’s still a lot we don’t know about SARS-CoV-2. It’s unclear exactly how it spread from animals to people. We don’t know whether you can catch it twice. Scientists aren’t sure yet that a vaccine would work.
And they also don’t know whether one version of the novel coronavirus is inherently more lethal than another. A team of Chinese scientists concluded, in a new study that hasn’t yet been peer-reviewed, that mutations in SARS-CoV-2 are “capable of substantially changing its pathogenicity.”
But Ben Cowling, a virologist at the University of Hong Kong, pushed back. “Currently there is no epidemiological evidence of variation in the severity profile of SARS-CoV-2 infections between different locations,” he told The Daily Beast.
“There are differences in fatality rates among confirmed cases between locations, but that can be explained by variation in testing practices,” Cowling added.
In other words, it might only appear that one strain of the novel coronavirus kills more people than another strain—perhaps because some countries and communities are doing more testing and more accurately attributing deaths to the virus.
Morrison, for one, proposed that mortality from COVID-19 could hinge on the patient’s genes, not the virus’s. “Perhaps a more important issue is that it is now becoming obvious that people vary greatly in their response to the virus, due mainly to genetic differences in our own immune systems.”
“Some people react very badly, with what has been described as a ‘haywire immune response,’ often leading to death even among young healthy people,” Morrison added. “Other people react not at all, with undetectable symptoms of COVID-19.”
The wide range of people’s responses to infection by SARS-CoV-2 could have huge implications. Potentially even more so than any prospect of the virus evolving into some weird new form.
“Apparently some infected people do not produce many antibodies in response to the presence of the virus in their bodies and thus do not have much in the way of future immune protection,” Morrison explained. “Other people fare much better, behaving in the manner we expect against viruses.”
Which is to say, our own genetic diversity could mean that, without a vaccine, many people might never become immune to the novel coronavirus, regardless of how the virus itself evolves.
