Hospital admissions for American COVID-19 in England rose from 0.81 to 1.20 per 100,000 people in one week as XFG became the dominant variant in England. The rise is showing up in hospital data, and London also saw admissions climb by nearly 80%.
Recent UK Health Security Agency numbers also show the proportion of positive COVID tests in hospitals moved from 5.9% to 7%. XFG, the official name for the strain people have dubbed American Covid or Stratus, belongs to the Omicron family and now appears in over half of samples tested in England.
World Health Organization tracking XFG
The World Health Organization is keeping an eye on XFG but has not labeled it a variant of concern. Virologists have been tracking XFG internationally for over a year, and the first sample showed up as far back as January of 2025. That places the variant in the wider Omicron lineage rather than in a new family of its own.
The practical risk sits highest with older people, especially over 75 and over 85, where hospitalizations are higher. People whose immune systems are not as strong, and people with certain chronic health conditions, are also at higher risk if they catch COVID.
England and London admissions
In England, the latest rise is not abstract for people already vulnerable. A patient over 85 arriving in hospital with COVID faces a different level of risk than someone younger and healthier, and the numbers now point to more admissions across the groups most likely to need care.
In London, the nearly 80% jump is the sharpest regional movement in the data. The broader picture is that COVID is still circulating, and the current increase is arriving as temperatures drop across the UK.
Vaccination remains the main shield
Getting vaccinated is still described as the best line of defense against getting really sick. The autumn booster campaign in the UK is aimed at the people who need protection most, which is the same group showing the highest hospitalization risk as XFG spreads through England.
What the figures do not settle is whether the rise in England will keep building into a larger autumn or winter wave. For now, the clearest signal is simple: admissions are up, XFG is dominant, and the oldest and most immunocompromised people remain the ones to watch most closely.
