Colorado officials on Tuesday reported the first known case in the United States of a person infected with the coronavirus variant that has been circulating rapidly across much of the United Kingdom and has led to a lockdown of much of southern England. Scientists believe the variant is more transmissible but does not make people sicker.
The case involves a male in his 20s who is currently in isolation in Elbert County, about 50 miles southeast of Denver, and has no travel history, according to a tweet from the office of Gov. Jared Polis.
“The individual has no close contacts identified so far but public health officials are working to identify other potential cases and contacts through thorough contact tracing interviews,” the tweet said.
A federal scientist familiar with the investigation, speaking on background to provide context for the announcement, said the fact that the person had no known travel exposure — in contrast with most known cases in which the variant has been seen outside the United Kingdom — indicates that this is probably not an isolated case, but rather the variant is likely spreading person to person.
“And we can expect that it will be detected elsewhere,” the federal scientist said.
Researchers have now detected the more transmissible variant in viral samples in at least 17 countries outside the United Kingdom, including as far away as Australia and South Korea, as of Tuesday afternoon. Officials in Canada had previously said they identified two cases, the first in North America.
While the variant appears to spread more easily, it is not leading to higher rates of hospitalizations or deaths, according to a new report from Public Health England, a government agency. Nor is there any sign that people who were infected months ago with the coronavirus are more likely to be reinfected if exposed to the variant, according to the report.
Scientists also believe these mutations will not allow the virus to escape the immune response incited by vaccines.
“This is cause for concern but not alarm,” the federal scientist said of the arrival of the variant in the United States, noting that there is no evidence it causes more severe infection. But the scientist added that the United Kingdom variant, as well as one spreading rapidly in South Africa, “appear to be more transmissible, meaning they can move rapidly through a population of people. And this is one more reason to do everything you can to prevent infection and its spread.”
Officials in the United States have been signaling since last week that the variant was likely already present, but simply undetected.
“I’m not surprised,” Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, said Tuesday. “I think we have to keep an eye on it, and we have to take it seriously. We obviously take any kind of mutation that might have a functional significance seriously. But I don’t think we know enough about it to make any definitive statements, except to follow it carefully and study it carefully.”
The variant has a higher attack rate, according to the UK report, which bolsters the hypothesis that the variant has outcompeted other versions of the coronavirus and is now the dominant variant across much of the United Kingdom. Among people known to have been exposed to someone already infected with the variant, 15.1 percent became infected. People exposed to someone infected with the non-variant version had a 9.8 percent infection rate.
That difference suggests the variant is more transmissible, though the health agency said more investigation is needed to bolster the hypothesis.
The working theory among many scientists is that the increased transmissibility of the variant, known as B.1.1.7, is driven by mutations that have altered the spike protein on the surface of the virus. The variant has 17 mutations — eight of which alter the spike protein.
Precisely how those changes are leading to more infections is unknown. The virus may be binding more easily to receptor cells in the human body, or replicating more easily and driving higher viral loads, enhancing viral shedding by someone who is infected. Another possibility is that people are shedding virus for a longer period, upping the chances of passing along the virus.
“Preliminary evidence suggests that the new variant does not cause more severe disease or increased mortality,”said Susan Hopkins, a senior medical adviser to Public Health England, in a statement released Tuesday.
The newly published data echo the findings in a separate study published last week, based on modeling and hospitalization data — and not yet peer-reviewed — that estimated that the variant is 56 percent more transmissible but doesn’t appear to alter the lethality of the virus.
“The good news is that B117 does not seem to cause much more severe disease, and there’s no evidence that it is managing to evade the immune system, which means vaccines are expected to protect against it,” William Hanage, an epidemiologists at the Harvard T. H. Chan School of Public Health, said Tuesday after reviewing the new report. “The bad news is that B117 does appear to be much more transmissible.”
Research findings on coronavirus variants have been at times ambiguous, and scientists stress that they are still trying to tweeze reliable signals from noisy data. Several false alarms have been sounded about virus mutations in the past. A major challenge is discerning whether a virus variant is spreading rapidly because it has a competitive advantage based on its genetic and structural differences, or is simply lucky, having arrived early to a location or leveraged a few superspreader events to gain dominance.
But with the United Kingdom seeing a severe winter surge of infections, public officials are taking no chances and have effectively locked down southern England, including London. Other countries have banned travelers from the United Kingdom.
The United States, despite having the world’s highest number of documented infections, has a weak track record in publishing genomic sequences, the process that enables researchers to track changes in the virus. Most sequences have been published by academic or private research institutions. By contrast, the United Kingdom has a national health system with a robust surveillance system.
“The U.K. made the decision in the spring to do this. The U.S. has sequencing equipment and infrastructure. As with many things in this pandemic, it was not executed the way it should have been,” said Neville Sanjana, a geneticist at New York University.
“The UK is being punished for having information. No other country has any idea what viruses they have,” said Jeremy Luban, a virologist at the University of Massachusetts Medical School. “ The lack of virus sequencing and case tracking in the USA is a scandal.”
The novel coronavirus, SARS-C0V-2, mutates at a slow rate, and scientists do not think the genetic changes seen in the variant so far are sufficient to allow it to elude the vaccines now being administered to millions of people in many countries. But the coronavirus is a moving target and these mutations require surveillance.
Even without the mutations, the coronavirus has been and will continue to be highly contagious.
“The best way to stop infection, whatever the variant, is to stick to the rules — wash our hands, wear a face covering and keep our distance from others,” Hopkins said.
The new variant is being compared to a globe-saturating strain of the virus — known in shorthand as the “wild type” of the coronavirus — that is itself a mutant version of what originally was identified in Wuhan, China, a year ago.
All viruses mutate randomly and over time some of those mutations appear to confer some kind of advantage to the virus as in adapts to the human species. No mutation has been shown to make the virus more likely to be dreadly or cause a more severe illness.
But it appears that the coronavirus learned to spread more easily early in the pandemic. Every genomic sequence of newly infected people shows that the virus with a mutation known as D614G, which also affects the structure of the virus’s spike protein.
Francois Balloux, who directs the Genetics Institute at University College London, predicted on Twitter that it would take two more weeks of accumulating data to determine whether this new variant was indeed more transmissible.
Previously, Balloux and his colleagues combed through genome sequences, looking for evidence that common variants had increased transmissibility.
“We don’t see much,” he said, referring to a report published in Nature in November that found no signs of mutations that helped the virus to spread more easily. But he said that he “wouldn’t underestimate the evolutionary potential of SARS-Cov-2.”
