Overview

• WHO designated the XFG and XFG.3 lineages as the Stratus variant under monitoring on June 25
• After emerging earlier this year, Stratus grew from about 10% of cases in England in May to an estimated 40% by mid-July, while global sequencing data show it represents nearly one-quarter of samples
• Mutations in the variant’s spike protein are linked to higher transmissibility and partial evasion of antibodies from past infections and vaccinations
• Available data indicate no rise in disease severity or reduction in vaccine protection, with most infections remaining mild to moderate
• Persistent hoarseness offers a key diagnostic clue as experts caution that waning immunity and reduced booster uptake could drive fresh infection waves