After first being discovered in the United Kingdom in September, a mutated strain of COVID-19 was detected for the first time in the United States last Monday.
Known as B.1.1.7., experts at the Centers for Disease Control and Prevention said the new strain is more contagious and more easily transmitted than the original virus, but so far has not been proven to cause more severe illnesses or increased risk of death.
"Because the variants spread more rapidly, they could lead to more cases and put even more strain on our heavily burdened health care systems," said Dr. Henry Walke, incident manager for the CDC's COVID-19 response. "We need to be even more vigilant in our prevention measures to slow the spread of COVID-19."
The virus was first spotted in southeastern England and was later found to be responsible for a quarter of cases in London by November. By the week of Dec. 9, it was reportedly responsible for 60 percent of cases in the city, the CDC said. On Dec. 28, it was discovered on US soil in Colorado in a COVID-19 patient with no reported travel history, leading experts to believe the virus was spreading from person to person within the community. California identified the second case two days later in another patient with no travel history.
Florida reported its first case—and the third in the United States—on Dec. 31 in Martin County followed by New York on Monday. These patients also reported no travel history.
The strain has been detected in at least 33 countries, including Australia, Belgium, Brazil, Canada, Chile, China, Denmark, Finland, France, Germany, Iceland, India, Ireland, Israel, Italy, Japan, Jordan, Lebanon, Malta, The Netherlands, Norway, Pakistan, Portugal, Singapore, South Korea, Spain, Sweden, Switzerland, Taiwan, Turkey, the United Arab Emirates, the United Kingdom and the United States.
In October, South African experts identified a strain similar to B.1.1.7—named B.1351—that also appears to spread more easily but is not more severe, and the CDC said a third variant emerged this fall in Nigeria but there was no evidence to suggest it was more severe or transmissible.
According to the CDC, the United States has sequenced viruses from only around 51,000 cases; given that over 20 million cases have now been documented in the states, experts said the variant could have been around for a while before detection. In response to the lack of sequencing being performed, the CDC launched the National SARS-CoV-2 Strain Surveillance (NS3) program in November to increase the number and representativeness of viruses undergoing characterization. When fully implemented later this month, each state will send CDC at least 10 samples biweekly for sequencing and further characterization.
In addition, CDC’s COVID-19 response is actively seeking samples of interest, such as samples associated with animal infection and, in the future, samples from vaccine-breakthrough infections. Data from these efforts are continuously analyzed at CDC, and genomic data are rapidly uploaded to public databases for use by researchers and public health agencies.
Is the vaccine effective for the new variant?
Researchers believe current COVID-19 vaccines will likely protect against B.1.1.7, but more data is needed. The virus would "likely need to accumulate multiple mutations in the spike protein to evade immunity induced by vaccines or by natural infection," according to the CDC.
"From what we know from experience with this mutation and other mutations, it's unlikely to have a large impact on vaccine-induced immunity, or existing immunity from previous strains," said Dr. Greg Armstrong, director of the CDC's Office of Advanced Molecular Detection. Armstrong said it is unclear how the variant may respond to COVID-19 treatments, such as monoclonal antibody treatments.
What makes the new strain more contagious?
SARS-CoV-2, the virus that causes the disease COVID-19, acquires about one new mutation in its genome every two weeks, according to the CDC. The U.K. variant has several mutations that affect the "spike protein" on the virus surface that attaches to human cells.
"It’s able to bind to the receptors on cells better, and therefore is transmitted better," Dr. Anthony Fauci, the nation's leading infectious disease expert, said last week.