But the CDC said there was still no evidence of that.
“Based on the scientific understanding of viruses, it is highly likely that there are many variants evolving simultaneously across the world,” said a spokesman in a statement sent to CNN.
“In addition, there is a strong possibility that there are variants in the United States; however, it may take weeks or months to identify whether there is a single variant of the virus that causes COVID-19, fueling the outbreak in the United States similar to the increase in UK, “added the spokesman.
“Researchers have been monitoring US strains since the start of the pandemic, including 5,700 samples collected in November and December. So far, neither CDC researchers nor analysts have seen the emergence of a particular strain in the United States, as seen with the emergence of B.1.1.7 in the United Kingdom or B.1.351 in South Africa. “
It was not immediately clear why the White House issued a printed statement to states speculating about a new variant of the virus emerging in the United States. A government official told Jim Acosta of CNN that speculation began in connection with governors.
CNN obtained several copies of written statements sent to states last week.
“This wave of autumn / winter has been almost double the rate of increase in cases compared to spring and summer. This acceleration suggests that there may be a US variant that has evolved here, in addition to the UK variant that is already spreading in our communities and can be 50% more transmissible, “says the report.
“Aggressive mitigation should be used to match a more aggressive virus; without uniform implementation of an effective face mask (two or three layers and well-adjusted) and strict social distance, epidemics can quickly worsen as these variants spread and spread. become prevalent. “
The CDC is tracking instances of the variant seen for the first time in Britain. Regular coronavirus tests do not tell doctors if people are infected with a variant. To do this, laboratories need to perform much more detailed genomic testing.
So far, the CDC has reported Friday, 63 cases of people infected with a variant similar to one first detected in Britain have been reported in eight states: California, Colorado, Connecticut, Florida, Georgia, New York, Pennsylvania and Texas. But the CDC says there are probably many more cases.
What is unclear is whether these variants, which can facilitate the transmission of the virus to others, are causing the virus to spread explosively in the United States, parts of Europe and elsewhere.
All viruses mutate, and the coronavirus mutates at a relatively slow rate compared to, say, the flu. Researchers have been tracking changes in the virus as it spreads around the world and putting their findings in public databases like NextStrain and one called GISAID.
Academic researchers also said they were intrigued by the White House statement and said there was still no evidence that variant versions of the virus were driving the spread of the virus in the United States.
“I don’t know of a variant identified in the U.S. that could be responsible for the increase we’re seeing,” Scott Hensley, a virus and immunity expert at the University of Pennsylvania, told CNN.
“There are many reasons why infection rates have increased during autumn and winter,” added Hensley. This includes colder temperatures, which take people into the home and can also create a drier, colder air that helps spread viruses.
“The rise in cases does not necessarily need a genetic explanation,” he said.
Trevor Bedford of the University of Washington and the Fred Hutchinson Cancer Research Center, which helps maintain NextStrain, also said they saw no evidence of an American strain that is spreading more aggressively.
“We see no indication of a particular strain or strain contributing to a large number of cases in the fall / winter epidemic in the United States,” said Bedford, who studies the spread of viruses.
“There is no particular lineage that is growing and rapidly becoming a larger fraction of the epidemic (as seen in the UK and South Africa).”
This does not mean that there are no variants emerging in the US – coronaviruses, like many viruses, change over time and more are transmitted. But no specific version has changed the rate of spread, the researchers said.
The more the virus spreads, the more likely it is to happen, however, said Hensley.
“If you are a virus and have 300,000 shots on goal every day, there is a good chance that one of those shots will enter. Viruses are constantly making mistakes in their genomes, ”he said.
“The levels of viruses in our country are out of control,” he added.
“If there are a lot of viruses, there are a lot of opportunities for variant selection. If someone is concerned about the variants, the best thing you can do is to limit the amount of virus that is circulating. The best way you can do that is to vaccinate people and with social distance ”.