What doctors and virus experts are saying about the wave of American Covid sweeping Britain

From masks stuffed into coat pockets to plastic testing kits lined up by the bathroom sink, the rituals of the Covid years thankfully seem consigned to history for most of us.

Yet in recent weeks, an unwelcome phrase has begun creeping back into conversations in offices, schools and family WhatsApp groups: ‘I think I’ve got Covid.’

For after several years in which the virus that once brought Britain to a standstill had largely faded from everyday consciousness, it seems to be on the march again.

Latest figures from the UK Health Security Agency (UKHSA) show hospital admissions relating to Covid have jumped by almost 50 per cent in a week, while the proportion of hospital Covid tests coming back positive has risen from 5.9 per cent to 7 per cent.

In London, the increase is sharper still, with hospital admissions rising by almost 80 per cent in seven days. Among the over-85s – the most vulnerable age group – they have leapt from 7.08 to 12.43 per 100,000. Needless to say, far fewer people are testing for Covid these days, so the true scale of infection remains unknown.

It is enough to prompt an uncomfortable question many of us hoped we would never have to ask again: just how worried should we be?

The reassuring answer is, not nearly as worried as we were more than five years ago.

For while Covid is staging something of an autumn resurgence, the numbers remain a world away from the darkest days of the pandemic, when hospitals were overwhelmed and hundreds of Britons were dying every day. What’s more, symptoms are, by and large, much more manageable.

For now, that is, because keeping experts awake at night is the possibility that a coalition of winter bugs, including Covid, could hit the country together and inundate hospitals as happened in 2024 (more of which later).

‘Covid is increasing, but from a low level, which is not unexpected at this time of year,’ says Dr Matthew Siggins, lecturer in immunity and infection biology at the University of Surrey. ‘The most recent UKHSA data for England show weekly hospital admissions have risen from 0.81 to 1.20 per 100,000, which is still classified as a baseline level.’

The strain dominating infections is XFG, commonly referred to as ‘Stratus’ and nicknamed ‘American Covid’.

First detected in January 2025, it has spread, both here and in the US, causing many of the familiar symptoms associated with Covid. But in addition to coughing and fever, some doctors are reporting gastrointestinal problems among Stratus patients.

London GP Dr Renée Hoenderkamp says she has noticed a marked change in patients coming through her door complaining of sore throats, headaches, runny noses and fatigue.

‘In the past ten days to three weeks in general practice my lists have definitely changed to people with these symptoms,’ she says. ‘It’s definitely about.’

Of course, such symptoms could easily be mistaken for any number of seasonal viruses. ‘It’s very flu‑like, actually, which is probably the fairest way to describe it,’ Dr Hoenderkamp says of the latest strain.

She suspects she recently had Covid after temporarily losing her sense of taste, but otherwise experienced little more than a runny nose and fatigue. ‘That’s the reality for most people,’ she says. But emphatically not everyone. One fiftysomething mother-of-two from south-west London, who considers herself impervious to illness, told the Daily Mail how she was ‘floored’ for five days after falling ill last Friday. Although she did not take a Covid test, her illness coincided with the current wave of respiratory infections.

‘I’m never ill – I literally can’t remember the last time I took a sick day,’ she says. ‘But I was absolutely exhausted, with a temperature, cough and really painful flu-like aches in my legs and joints.

‘There were times in the morning when I’d think: “I’m fine, get your act together.” But by lunchtime I’d have to go back to bed. I slept through a lot of it.’

Her teenage daughter, meanwhile, who fell ill a few days previously, was still ill after ten days.

‘She had a really bad headache, sore throat and cough, a raging temperature and was completely exhausted,’ her mother says. ‘She developed an eye infection and a chest infection and eventually we took her to the doctor because we thought: “This is crazy.”

‘The doctor said she was the third person he’d seen that day with something similar.’

Professor Emma Wall, a clinical professor of infectious diseases at Queen Mary University of London, says: ‘Some people will be floored by an infection while others remain asymptomatic, and we don’t yet completely understand the biology behind that.

‘Some people have very effective T-cells [a type of white blood cell] that clear an infection before you know you’ve got it, while in others they can stimulate an inflammatory response to the infection that affects the whole body, which is probably part of what makes some people feel so ill.’

Perhaps the most important context comes from the death toll. The latest readily available UKHSA figures show seven registered deaths involving Covid in England in the week ending August 28, compared with six the previous week.

Earlier this year the weekly figure was considerably higher – there were 61 deaths in a week in mid-January.

So while infections and hospitalisations are unmistakably heading upwards, there is nothing remotely resembling the mortality crisis of the original pandemic.

At its peak in January 2021, 25,889 Covid deaths were registered in England – although, in nearly 8 per cent of those cases, Covid was listed as a ‘contributory factor’ rather than the underlying cause. For the overwhelming majority of otherwise healthy people, therefore, Dr Hoenderkamp believes there is little reason to be alarmed.

Her advice is essentially the same common sense that applies to other respiratory illnesses: if you are running a high temperature or feel particularly unwell, stay at home. ‘You would do the same with flu,’ she adds.

Unlike the heavy-handed instructions of 2020, however, she believes those with coughs or sniffles, meanwhile, should go about their business as usual – and not be judged for it.

‘The fact is we can’t tell everyone with a cold to stay at home because the world would come to a halt,’ she says. ‘A lot of people don’t realise that coughs or upper respiratory tract infections can last for up to eight weeks. You can’t tell people to isolate for that long. Ultimately, we have to accept that illness is around us and we can’t live in a bubble.’

Even so, not everyone appears quite ready to consign the heightened precautions of the pandemic years to history.

For some stalwarts, mask-wearing is still a feature of every-day life. Last week, the Daily Mail reported the story of the Last Ditch Bar in Greenfield, Massachusetts, which found itself at the centre of a ferocious online backlash after dropping – for one night only – its requirement that every customer wear a mask.

The owners were branded ‘eugenicists’ intent on murdering the sick – a sentiment that gets short shrift from Dr Hoenderkamp, who brands mask-wearing ‘a nonsense’.

‘I think the evidence is really clear now that a surgical mask cannot protect you from Covid,’ she says. ‘Most people wearing them are virtue-signalling.’

More significant is the role of immunity. ‘Most people still have substantial immunity from previous infection and vaccination’, says Dr Siggins. ‘That immunity does not always prevent infection, and it can fade over time, so reinfections still occur. However, protection against serious illness is generally much stronger.’

He adds: ‘While the virus continues to change, there is no evidence that the variants circulating in the UK are causing more severe disease.’

Most people have developed remarkably broad immunity to Covid, says Professor Wall, who, in addition to her role at Queen Mary University, leads a study at the Francis Crick Institute which has been tracking the immune responses of 800 predominantly healthy London adults since 2020.

That research is largely reassuring, as it shows that after repeated exposure through vaccination and infection, immunity is strong, even to new variants.

‘Every time a new variant turns up, most of the population we study already has some pre-existing immunity to it,’ she says.

In effect, it can still evade enough of our defences to replicate in the nose and be passed to somebody else, sometimes without causing symptoms.

But deeper protection in the immune system means for most healthy people it is far less able to invade the body and cause serious illness.

There is, however, an important caveat: Evidence increasingly suggests that repeated infections may increase the risk of Long Covid.

Professor Wall, who also works in a Long Covid clinic at University College London Hospitals NHS Trust, says new patients are still being referred, including people developing the condition after their fourth or fifth infection.

‘For most people, infection going round is harmless, and may actually boost immunity,’ she says. ‘But there are clinically vulnerable adults who are at risk, and there are also people who will either get Long Covid or experience a relapse.’

Researchers are continually monitoring emerging variants for mutations that could allow the virus to evade existing immunity more substantially. ‘We haven’t identified any mutations we think are really risky,’ Professor Wall says reassuringly.

That does not, however, mean scientists can guarantee there is nothing nastier waiting around the corner. Britain has already experienced the pressure created when several viruses surge.

In December 2024, hospitals in England were hit by what the then NHS England medical director Professor Sir Stephen Powis described as a ‘tidal wave’ of flu and other winter viruses. The ‘quademic’ of flu, Covid, RSV (a common respiratory virus) and norovirus led to an average of nearly 1,900 beds being taken by flu patients in the first week of December that year – 70 per cent up on the week before and more than three times higher than the same period in 2023.

Scientists remain vigilant. ‘We expect the traditional winter spikes of flu and rhinoviruses, while Covid looks as though it can come at any time,’ Professor Wall says. ‘So we remain under surveillance. That helps us work out who needs to be vaccinated and with which vaccine.’

Overall, then, the message is: don’t worry… too much.

‘We need to accept that coronaviruses have always been with us and will continue to be,’ Dr Hoenderkamp says. ‘There have always been cold viruses, and Covid is now one of them.’