New COVID-19 variant 'Stratus' spreading in US, UK; know symptoms
What's the story
A new COVID-19 variant, called "Stratus," is spreading rapidly in the United States and the United Kingdom. The Centers for Disease Control and Prevention (CDC) has reported high levels of the XFG variant in wastewater across 19 states, including Nevada, Utah, Connecticut, and Delaware. In England too, Stratus and NB.1.8.1 (known as Nimbus) are now the most common variants circulating.
Variant monitoring
Variant under monitoring by WHO
The World Health Organization (WHO) has classified the XFG variant as a "variant under monitoring." Compared to other variations that are now in circulation, such as the new "Nimbus" NB.1.8.1, XFG was estimated to have the highest relative growth worldwide. The UK Health Security Agency (UKHSA) has noted a 7.6% increase in coronavirus cases across England by September 10, although it's unclear how many are due to the XFG variant.
Variant characteristics
Symptoms and severity of new strain
The XFG variant, first detected in Southeast Asia in January 2025, is a recombinant hybrid of two Omicron subvariants. It is slightly more transmissible but does not cause more severe disease than previous strains. Common symptoms of the Stratus variant include sore throat, cough, fever or chills, shortness of breath, fatigue, loss of taste or smell, vomiting, diarrhea, and muscle aches. The WHO expects existing COVID-19 vaccines to remain effective against symptomatic and severe disease caused by this new strain.
Health guidance
What do health experts recommend?
In light of the rising COVID-19 cases, health experts recommend Americans to stay up-to-date with vaccinations and continue protective measures. The Food and Drug Administration (FDA) has approved updated vaccines for high-risk individuals over 65 or with underlying health conditions. Pediatric and obstetric groups also recommend vaccination for children and pregnant or lactating women.