In August, the figures began to change, initially subtly. When September arrived, the UK Health Security Agency’s data became difficult to ignore: hospitalizations had increased to almost 4,939 from just 950 weeks prior, COVID cases had increased by 230 percent in a single month, and a sizable portion of those positive tests were linked to the same variant, XFG, or, as many on social media have begun to refer to it, “American Covid.”
In a strict sense, XFG is not new. It has been circulating in various forms for around a year after it was originally sequenced in the US in January 2025. Health officials have been quick to warn that the “American” label is a little deceptive; the moniker represents where it was first identified, not where it originated. However, labels endure. And this one has, for sure. Due to its nature as a recombinant strain, which is a genetic hybrid of two existing Omicron subvariants, LF.7 and LP 8.1.2, stitched together into something that carries features from both parents, the variant is also known as Stratus and, somewhat dramatically, “Frankenstein,” in some parts of the internet.
The anecdotal evidence was all over the place for anyone who spent time on Reddit or X this week. “I’ve been sick for ages now and just found out about that American Covid going around the UK,” a user wrote. Another reported what seems like a classic XFG experience: a week-long sore throat that progressively turned into a head cold, followed by a two-week-long wave of exhaustion and fever.
One fairly unique trait of XFG compared to previous strains has been observed by clinicians: a peculiar croaky, raspy voice that patients frequently report on their own. It’s a minor detail, but the kind that suggests something is a little off is making the rounds.
The symptom profile, aside from the throat problem, is fairly well-known: cough, fever, headache, muscle aches, shortness of breath, and sporadic loss of taste or smell. More than 30 related symptoms are being monitored by the UKHSA, demonstrating the breadth of possible presentations. When it comes to the severity question, officials are being cautious and consistent.
According to available evidence, XFG does not appear to cause more serious illness than other strains currently in circulation. Yes, hospitalization rates are increasing, but they don’t seem to be skyrocketing on their own, which would indicate a more deadly variant. Instead, they seem to be climbing in tandem with overall case numbers. The difference is important. It makes the difference between many more individuals contracting a treatable illness and the same number of people contracting a more serious one.
It’s difficult to ignore the timing. Every autumn, a season that seems to arrive a bit sooner than anticipated, brings with it this moment of collective reckoning with Covid. Health officials say two reasons are currently driving up the numbers. The first is winter, when it’s colder, wetter, and everyone is crammed indoors and closer to one another. Waning immunity comes in second. About a year has passed since the last major wave, and the population’s immunity from vaccinations and previous infections has weakened to the point where people are once again significantly more vulnerable. These two are not shocking. They are both genuine.
Modeling indicated that XFG will be the predominant variant this season, thus, the current autumn booster was specifically designed to cover it and related strains. The modeling proved to be accurate. Adults over 75, inhabitants of assisted living facilities, and children older than six months with weakened immune systems are also eligible for priority. Private vaccination is an option for everyone else; it usually costs about £98 per dose, which is not trivial but still affordable for people who choose to be protected.
It’s not too difficult to know what to do once symptoms start. The NHS no longer advises testing for the majority of people, but it does suggest avoiding contact with vulnerable people for at least ten days and staying at home if you have a fever or feel too sick to go about your day. It’s advice that doesn’t sound overly dramatic. However, seeing hospital admissions increase fourfold in just one month serves as a silent reminder that the fundamentals are still more important than they may first appear.