There is no evidence that the rise in COVID-19 cases in the US is due to either the recently identified UK SARS-CoV-2 or a strain that arose in the US, officials from the US Centers for Disease Control and Prevention say, according to the Washington Post. However, it notes that scientists' ability to detect new variants is limited.
"The general consensus is there's no single variant driving current US cases. That said, we need to be on the lookout for these variants of concern," Duncan MacCannell from the CDC's Office of Advanced Molecular Detection said earlier this week, according to the Post.
He estimates that less than 0.5 percent of viral transmissions in the US are of the B117 strain identified last month in the UK, but tells the Post that it is likely to make up a greater portion of cases in the coming weeks.
The CDC is on track to increase the number of viral samples in the US that undergo genome sequencing, it notes. Last week, CNN reported that the CDC aimed to double the number of viral samples sequenced in the US from 3,000 samples a week to about 6,500 samples. However, researchers have noted that there is no nationwide sequencing program.
William Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health likewise tells the Post that in the US "surveillance is such that we'd not detect any such variant until it was already emerged and well established."