US sees rising COVID infections driven by new ‘Stratus’ variant

The newly identified XFG ‘Stratus’ COVID-19 variant is fueling a surge in infections across the United States. According to the Centers for Disease Control and Prevention (CDC), wastewater monitoring as of September 20 shows moderate national viral activity, while 19 states including Nevada, Utah, Connecticut, and Delaware report high or very high levels.

CDC data indicates that the XFG variant accounted for less than 3% of infections in early May 2025 but rapidly rose to represent 85% of COVID cases during the four weeks ending September 27. UK government genomic surveillance data notes that XFG sub-lineages, including XFG 3, XFG 5, and XFG  3 4 1, now dominate the circulating virus population.

First detected in Southeast Asia in January 2025, XFG is a hybrid of two Omicron sub-strains and is considered slightly more transmissible, partly due to immune evasion properties. However, available data suggest it does not cause more severe disease than previous Omicron variants.

The World Health Organisation (WHO) confirms that existing vaccines remain effective against symptomatic and severe illness caused by XFG.

In India, the ICMR-National Institute of Virology (NIV) is closely tracking emerging variants, including JN 1 16 and XFG recombinant lineages LF 7 and LP 81 2. Dr Naveen Kumar, Director of ICMR-NIV, stated that these variants have not caused severe infections despite a recent rise in active cases.

(With inputs from syndicated feed)