Overview

• The Stratus lineages XFG and XFG.3 now make up roughly one-third of COVID-19 cases in England, overtaking the previous Nimbus subvariant.
• WHO has designated XFG as a variant under monitoring after its share of global cases surged from about 7% to nearly 23% within a month.
• UKHSA experts report no evidence of increased severity or reduced vaccine effectiveness against Stratus, despite its unique spike protein changes.
• Clinicians have identified hoarseness—a scratchy or raspy voice—as a hallmark symptom distinguishing Stratus infections.
• Reduced testing and lower spring booster uptake are hindering variant tracking and raising worries that waning immunity could trigger a new infection wave.