COVID-19 and the Stratus Variant

COVID-19 Subvariant XFG

COVID-19 cases are rising in Texas, and the XFG COVID-19 variant, aka "Stratus," is spreading rapidly in the U.S. as cases climb. XFG is a recombinant or hybrid of two existing omicron strains, LF.7 and LP.8.1.2. XFG was first detected in January in Southeast Asia and given its cloud-themed nickname "Stratus" by evolutionary biologist T. Ryan Gregory. The World Health Organization currently lists Stratus as a "variant under monitoring," the lowest of the WHO's alert tiers.

Rapid Global Spread

As of June 22, there were 1,648 XFG sequences submitted to GISAID from 38 countries, representing 22.7% of globally available sequences. This was a significant rise from 7.4% four weeks prior. During the four-week period ending August 30, XFG accounted for an estimated 74% of COVID cases in the United States. Data from Stanford's WastewaterSCAN program shows the strain makes up approximately 82% of variants detected in Bay Area locations.

Symptoms and Characteristics

According to the CDC, symptoms include congestion, cough, fatigue, headache, and mild fever, plus cough and sore throat. Some reports have linked Stratus to a particularly severe sore throat, sometimes called "razor blade throat". One of the most noticeable symptoms is hoarseness, which includes a scratchy or raspy voice. Stratus has shown "a wider range of symptoms," including gastrointestinal issues, though most cases remain mild.

Transmissibility and Severity

XFG is a subvariant of Omicron that shows improved immune evasion, meaning protection from past infection and vaccination doesn't work as well. However, the WHO assesses the public health risk posed by XFG to be "low," and current data do not indicate that Stratus causes more severe illness. These sublineages of Omicron are all highly transmissible and tend to cause less severe disease compared to previous variants of concern.

Cloud-Themed Naming

The decision to assign the XFG variant the nickname "Stratus" was born from the observation that "Nimbus (NB.1.8.1) and Stratus (XFG) are the two main variants competing for dominance globally". Like meteorological stratus clouds, which form in low horizontal layers, this variant spreads in a widespread, persistent pattern across populations.

Bottom Line

The Stratus variant represents the latest evolution of COVID-19, demonstrating increased transmissibility while maintaining relatively mild symptoms. With kids going back to school, experts warn that "a sniffle is likely going to be COVID" given the variant's high transmission rate.