Beware Overblown Claims of Coronavirus Strains

[Celerity]

The Problem With Stories About Dangerous Coronavirus Mutations

There’s no clear evidence that the pandemic virus has evolved into significantly different forms—and there probably won’t be for months.

https://www.theatlantic.com/health/archive/2020/05/coronavirus-strains-transmissible/611239/



As if the pandemic weren’t bad enough, on April 30, a team led by scientists at Los Alamos National Laboratory released a paper that purportedly described “the emergence of a more transmissible form” of the new coronavirus, SARS-CoV-2. This new form, the team wrote, “began spreading in Europe in early February.” Whenever it appeared in a new place, including the U.S., it rapidly rose to dominance. Its success, the team suggested, is likely due to a single mutation, which is now “of urgent concern.” The paper has not yet been formally published or reviewed by other scientists. But on May 5, the Los Angeles Times wrote about it, claiming that “a now-dominant strain of the coronavirus could be more contagious than [the] original.” That story quickly went … well … viral.

But “the conclusions are overblown,” says Lisa Gralinski of the University of North Carolina, who is one of the few scientists in the world who specializes in coronaviruses. “To say that you’ve revealed the emergence of a more transmissible form of SARS-CoV-2 without ever actually testing it isn’t the type of thing that makes me feel comfortable as a scientist.” She and other virologists I’ve spoken with who were not involved in the Los Alamos research agree that the paper’s claims are plausible, but not justified by the evidence it presents. More important, they’re not convinced different strains of the coronavirus exist at all.

“We have evidence for one strain,” says Brian Wasik at Cornell University. “I would say there’s just one,” says Nathan Grubaugh at Yale School of Medicine. “I think the majority of people studying [coronavirus genetics] wouldn’t recognize more than one strain right now,” says Charlotte Houldcroft at the University of Cambridge. Everyone else might be reasonably puzzled, given that news stories have repeatedly claimed there are two, or three, or even eight strains. This is yet another case of confusion in a crisis that seems riddled with them. Here’s how to make sense of it. Whenever a virus infects a host, it makes new copies of itself, and it starts by duplicating its genes. But this process is sloppy, and the duplicates end up with errors. These are called mutations—they’re the genetic equivalent of typos. In comic books and other science fiction, mutations are always dramatic and consequential. In the real world, they’re a normal and usually mundane part of virology. Viruses naturally and gradually accumulate mutations as they spread.

As an epidemic progresses, the virus family tree grows new branches and twigs—new lineages that are characterized by differing sets of mutations. But a new lineage doesn’t automatically count as a new strain. That term is usually reserved for a lineage that differs from its fellow viruses in significant ways. It might vary in how easily it spreads (transmissibility), its ability to cause disease (virulence), whether it is recognized by the immune system in the same way (antigenicity), or how vulnerable it is to medications (resistance). Some mutations affect these properties. Most do not, and are either silent or cosmetic. “Not every mutation creates a different strain,” says Grubaugh. (Think about dog breeds as equivalents of strains: A corgi is clearly different from a Great Dane, but a black-haired corgi is functionally the same as a brown-haired one, and wouldn’t count as a separate breed.)

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[Laelth]

1. This is useful information.

k&r for visibility.

-Laelth

[Phoenix61]

2. Happy to read this. I'm going to remember

the analogy about the dogs. That’s a great way to explain it.

[underpants]

3. Too many "studies" are being rushed out

[crickets]

5. Agreed. Peer review takes time but it's required for good reason. nt

[Strelnikov_]

4. Agree . . . I have been seeing FUD related articles for weeks now

New York/Italy/Spain was all about infectious dose, and where said dose was administered.

[BGBD]

6. Good article.

I've heard other people who would know describe multiple strains, but that the "mutations" between them are minuscule and wouldn't impact vaccine effectiveness against them.

You have to remember that all viruses change slightly even from one person to another,

Consider it like people. There are no two people exactly alike, but we are similar enough that there are essentially the same. If we thought of ourselves as strains, that would probably equate closer than anything else to races. But again, while there are differences in say black and white people, we aren't really very different other than some very small things.