Covid-19 Covid-19 New Covid Variant XFG Spreads Quickly in UK – Mild Symptoms but Watch for HoarsenessBy WTX News Editor A new Covid-19 variant known as Stratus (XFG and XFG.3) is rapidly spreading in the UK. The UK Health Security Agency reports these subvariants account for around 30% of cases in England, rising sharply in recent weeks.