R.1 Variant With Dangerous Mutation Has Spread Most in These States

The R.1 variant of COVID-19, which has been found to carry a dangerous mutation, has spread to 47 states since it was first recorded in the U.S. in March. It has been most prevalent in Maryland, according to the Outbreak.Info tracking project.

More than 2,250 sequences of R.1 have been detected across the U.S. in total—but there have been no new cases for the past seven weeks.

The Outbreak.Info data for Maryland shows that R.1 was sequenced in nearly 2 percent of samples from the state.

Next come West Virginia, Kentucky and Pennsylvania, all of which have an R.1 prevalence of more than 1 percent.

The most recent U.S. case of R.1 was detected on August 6. Worldwide, there have been just over 10,500 cases recorded, with the most recent on August 7.

R.1 has not been designated as a variant of concern or a variant of interest by the World Health Organization (WHO). In addition, it is not on the Centers for Disease Control and Prevention (CDC) list of variants being monitored, the next tier down.

However, William A. Haseltine, a disease researcher and former professor at Harvard Medical School, has described R.1 as a "variant to watch" in an article for Forbes.

Haseltine said the strain had established a foothold in Japan—where it was first identified—and in the U.S., adding that it had mutations in common with several variants of concern.

R.1 has the E484K receptor-binding mutation, which is thought to confer resistance to antibodies and make the virus tougher to defend against. The same mutation is present in the Beta, Gamma, Eta, Iota and Mu variants of COVID.

Haseltine added that R.1 also has a unique mutation known as G439R, which is worthy of further study.

He concluded in his Forbes article, published on September 20: "In addition to several mutations […] in common with variants of concern, R.1 has a set of unique mutations that may confer an additional advantage in transmission, replication, and immune suppression."

The CDC has studied a COVID outbreak associated with the R.1 variant, at a Kentucky nursing home in March.

Altogether 46 residents and staff of the home were infected, but despite R.1's mutations the CDC said vaccinated residents and staff were 87 percent less likely to have symptomatic infections compared to those who were unvaccinated.

By a significant margin, Delta remains the most widespread variant of COVID in the U.S. right now. According to CDC data for the week ending September 18, the variant accounted for 98.4 percent of samples collected.

Research lab
A stock photo shows a scientist using a microscope to examine a sample. Sequencing data has found more than 2,250 cases of the R.1 variant in the U.S. since March. Niphon Khiawprommas/Getty