Why are new coronavirus variants emerging in the U.S.?
Nearly one year into the pandemic, Covid-19 is spreading at record high rates in the United States, and with it, new variants of the virus are emerging. Last week, researchers in Ohio said they identified two unique variants in Columbus.
Experts agree that it’s not surprising that new variants have emerged in the U.S., but stress that the virus’s unchecked transmission in the country provides ample opportunities for it to mutate. The best way, therefore, to crack down on new variants is to stop the spread, they say.
“The only way to [stop emergence of new variants] is to stop the spread of the virus,” said Ben Bimber, a research professor at Oregon Health and Science University.
If there’s more people infected, there’s simply more virus out there and it has more opportunities to mutate.
“Every time the virus replicates, it’s an opportunity to mutate,” he said. “If there’s more people infected, there’s simply more virus out there and it has more opportunities to mutate.”
When the coronavirus infects an individual, it enters the cells and makes copies of itself. “Every time the virus copies itself, there’s a chance to introduce errors,” Bimber said. “If the virus is replicating in people, it will slowly accumulate mutations.”
Oftentimes, these errors, or mutations, are meaningless. But in some cases, they may give the virus a survival advantage — making it more contagious, for example, or more resistant to treatments or vaccines. On the other hand, some mutations can render the virus weaker.
It’s unclear how the two variants recently identified in Ohio will affect how the virus behaves.
The findings on those variants were posted last Friday on the online preprint server BioRxiv, meaning they have not yet been peer-reviewed. In the study, the researchers analyzed the genetic sequences of more than 220 coronavirus samples obtained in the Columbus area from April 2020 through early January 2021.
One of the variants identified in Ohio contains a mutation on the virus’s spike protein called N501Y — the same mutation found in the more contagious U.K. variant, as well as the South African variant, Dr. Dan Jones, vice chair of the division of molecular pathology at Ohio State University Wexner Medical Center, said during the media briefing last Wednesday. The variant didn’t arrive from someone abroad; rather, by analyzing other small changes in the variant’s genetic code, the researchers were able to determine that it emerged independently, in the U.S.
William Hanage, an associate professor of epidemiology at the Harvard T.H. Chan School of Public Health, said he was not surprised by the detection of new variants, particularly the one with the N501Y mutation, “because of the fact that it’s happened so many times.” In addition to emerging in the U.K. and South Africa, that particular mutation has also been detected in Brazil.
The other variant contained a combination of three mutations that haven’t been observed together before, the researchers said. While the N501Y mutation was only found in one sample, this variant, with three mutations, quickly became predominant in the samples the researchers tested in December and January.
Jones told NBC News that vaccination is key to both stop the spread of variants, as well as reduce the odds of new variants emerging.
“The larger your pool of [susceptible] patients, the more possibility for a mutation to survive and emerge,” he said. “It has to pass from person to person, so if you’re not getting a lot of infection in the population [because of vaccination], then even an important mutation may just peter out, because the person who was infected doesn’t transmit the virus to anyone else.”
Even “having an optimally fit, pathogenic change in the virus doesn’t do any good if it keeps meeting a wall of vaccinated people,” Jones added.
The Centers for Disease Control and Prevention said it is “aware” of the Ohio variants, and issued the same statement it gave on Jan. 8, following a controversial report from the White House Coronavirus Task Force that speculated that a U.S. variant might be driving the recent surge in cases in the country.
That statement said that while “it is highly likely there are many variants evolving simultaneously across the globe,” the CDC has “not seen the emergence of a particular variant in the United States as has been seen with the emergence of B.1.1.7 in the United Kingdom or B.1.351 in South Africa.”
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However, the statement noted “there is a strong possibility there are variants in the United States; however, it could take weeks or months to identify if there is a single variant of the virus that causes Covid-19 fueling the surge in the United States similar to the surge in the United Kingdom.”
New variants are expected and not all are a cause for concern, said Angela Rasmussen, a virologist at the Georgetown University Center for Global Health Science and Security.
“We should worry when a variant is accompanied by epidemiologic evidence such as that observed in the U.K.” — she said, referring to the surge in cases seen as that country’s variant grew more widespread — “or if there’s a significant association with increased disease severity.”
But “regardless of emergent variants, we must emphasize reducing transmission of all variants,” Rasmussen said. That means wearing a mask, avoiding crowds and practicing good hand hygiene.
Bimber agreed that it was too early to draw any conclusions about the variants detected in Ohio.
“This is a really fast moving space and it takes time to really evaluate the effects of these” new variants, he said. “This won’t be the last one and there are definitely going to be new variants that emerge in the virus as it infects more individuals.”