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Why Viruses Mutate: Breaking Down The New Coronavirus Variant


More than 20 million people have now been confirmed to be infected with the coronavirus in the United States. About 350,000 Americans have died of COVID-19. Now health officials have detected the new variant of the virus first seen in the U.K. in California, Colorado and Florida. Because it is believed to be more contagious than previous versions, there are concerns this could mean even more infections across the country. NPR global health correspondent Michaeleen Doucleff joins us now. Thanks so much for being with us.


SIMON: I understand this version of the virus has a set of mutations in its genes. To try and understand it, where do those mutations come from?

DOUCLEFF: Yeah. So this version has actually 17 mutations. And mutations in viruses crop up all the time when the virus grows inside a person, specifically when it reproduces and makes a bunch of copies of itself. I talked to Bettie Steinberg. She's a virologist at the Feinstein Institutes for Medical Research on Long Island. She says that to grow inside a person, the virus has to make copies of its genes.

BETTIE STEINBERG: It's just like copying a manuscript. Sometimes there's typos. The virus just makes random mistakes when it gets copied.

DOUCLEFF: In the vast majority of cases, these mistakes are harmless, or they even weaken the virus. But in rare instances, mutations can help the virus. They can give it this little boost or advantage over the other versions.

SIMON: So what's happened with this new variant? Have the mutations - can they tell so far? - given the virus what amounts to an infectious advantage over the previous version?

DOUCLEFF: Yeah. So scientists first detected this new variant, like you said, in the U.K. back in September. By December, it had become the dominant one in London. And it is responsible for the huge surge in cases there now. This variant has also spread to at least 32 other countries. And right now, here in the U.S., scientists think it's still pretty uncommon. But they believe that could change pretty fast, like in the next month or two, because they estimate the variant is about 50% more transmissible than the previous ones.

SIMON: And how does that happen? Why would mutations make a virus more contagious?

DOUCLEFF: Yeah. So they're not quite sure yet, but they have some data that is pointing to two main hypotheses. Stephen Goldstein studies virus evolution at the University of Utah. He says that there's some evidence that the new variant generates more virus particles inside a person's nose or respiratory tract, possibly a lot more.

STEPHEN GOLDSTEIN: When you expel virus when you talk or breathe, you're going to get more virus out than somebody who doesn't have this variant simply because you have more virus in you to begin with.

DOUCLEFF: The other hypothesis is that the new variant binds to human cells more easily, so people can get infected with lower doses of the virus.

SIMON: Can this variant be stopped?

DOUCLEFF: Well, the good news here, Goldstein says, is that all the measures that we've been doing so far to stop the previous variants will stop this new one.

GOLDSTEIN: It's not a new variant that can go through masks. Those things will work, but it requires a greater level of rigor in the adherence to those things.

DOUCLEFF: For example, right now, if, say, only 80% of people in a community are following these guidelines, then to stop this new variant, you would need something like 90% or 95% of people to follow the guidelines. And all the scientists I spoke to say the vaccine needs to roll out as quickly as possible because, so far, scientists do believe that the vaccine will still be effective against this new version of the virus.

SIMON: NPR's global health correspondent Michaeleen Doucleff, thanks so much for being with us.

DOUCLEFF: Thank you, Scott. Transcript provided by NPR, Copyright NPR.

Michaeleen Doucleff, PhD, is a correspondent for NPR's Science Desk. For nearly a decade, she has been reporting for the radio and the web for NPR's global health outlet, Goats and Soda. Doucleff focuses on disease outbreaks, cross-cultural parenting, and women and children's health.