Colorado has discovered a case of a highly infectious coronavirus variant first detected in the United Kingdom, Colorado Governor Jared Polis said on Tuesday, the first known case in the United States.
"Today we discovered Colorado’s first case of the COVID-19 variant B.1.1.7, the same variant discovered in the UK," Polis said on Twitter.
The strain, referred to by some experts as the B.1.1.7 lineage, is not the first new variant of the pandemic virus to emerge, but is said to be up to 70 percent more transmissible than the previously dominant strain in the United Kingdom.
More than 3,000 cases of the UK variant have already been reported in the UK and dozens of countries in Europe and around the world, according to the ECDC.
The main worry is that the variant is significantly more transmissible than the original strain. It has 23 mutations in its genetic code - a relatively high number of changes - and some of these are affecting its ability to spread.
One of the mutations in the new variant affects one of three genomic targets used by some PCR tests. This means that in those tests, that target area, or "channel", would come up negative.
"This has affected the ability of some tests to detect the virus," said Robert Shorten, an expert in microbiology at the Association for Clinical Biochemistry & Laboratory Medicine.
Since PCR tests generally detect more than one gene target, however, a mutation in the spike protein only partly affects the test, reducing that risk of false negative results.