Thousands of people across the UK are coming down with the "worst cold ever" as the country reopens from coronavirus lockdowns.
Stories about the "super cold" have dominated British media in recent weeks and there have been tens of thousands of internet searches for "worst cold ever".
Many have taken to Twitter, Facebook and TikTok to complain that they're unable to shake the bug.
Reported symptoms include "sandpaper throat", head and body aches, runny nose and fatigue, sometimes lasting weeks.
"Day eight I think of super cold. Losing track of time. Grim as hell," CNN producer Luke McGee wrote on Twitter.
Benjamin Butterworth from The i newspaper said, "Every bit of my body aches. Feel like I've run a marathon just from being awake. Seems 'the worst cold ever' might have got me."
While the symptoms overlap with Covid-19, "super cold" sufferers report testing negative for the virus.
Nearly 68 per cent of people in the UK are fully vaccinated against Covid-19, and the country has started offering booster shots ahead of winter.
British PM Boris Johnson watches as 88-year-old Nitza Sarner receives a Pfizer booster vaccination as he visits a Covid-19 vaccination centre at Little Venice Sports Centre, in London. (Photo / AP)
According to the UK's ZOE Covid Symptom Study, there has been increasing crossover in symptoms between Covid-19 and the cold.
At the beginning of the pandemic, the main distinguishing Covid-19 symptoms were thought to be fever, cough and loss of smell.
Millions of reports to the ZOE Covid Study app have since identified more than 20 symptoms of Covid-19, including headache, runny nose, sneezing and sore throat.
"Over the past 18 months the pattern of symptoms has changed as the virus has evolved and more people have been vaccinated," the website says.
"Many of the symptoms of Covid-19 are now the same as a regular cold, especially for people who have received two doses of the vaccine, making it hard to tell the difference."
The health science company says loss of smell or loss of taste are still the most important predictors of testing positive for Covid-19 rather than a regular cold.
"So it's an important symptom to look out for, whether you've been vaccinated or not," the website says.
Brits have also been warned to be alert for the signs that the super cold has developed into deadly pneumonia.
The Times reported earlier this month there had been an uptick in calls to GPs and the National Health Service's 111 hotline about autumn colds and flu.
A man wears a face mask as he walks in Piccadilly Circus, London. (Photo / AP)
The calls mainly related to difficulty breathing, particularly in patients aged 15 to 44.
Experts have said it's likely due to weakened immune systems after nearly two years of lockdowns and social distancing.
"It could well be that now common colds are resurging, because of the decline in social distancing and mask-wearing, that they are bouncing back and the respiratory tract has not had enough recent experience of respiratory infections to be able to mount that strong first-line defence," Professor Peter Openshaw from Imperial College London told The Guardian last month.
While the focus for the past 18 months has been on Covid-19, colds and flu have also been stopped in their tracks.
Now that people are socialising again and catching public transport, non-Covid respiratory illnesses are on the rise again.
"We've actually been seeing a rise in the number of coughs and colds and viral infections," London-based GP Dr Philippa Kaye told the BBC.
"We are mixing in a way that we haven't been mixing over the past 18 months. During those first lockdowns, we saw numbers of other [non-Covid] infections fall. We think that that was primarily due to the restrictions on meeting up."
Writing for The Sun, Dr Kaye said there was simply more virus circulating in the community this year.
She suggested people might be catching multiple bugs, resulting in prolonged illness.
"This year is like every single year, there is never just one cold, cough or virus doing the rounds," she wrote.
"So if you feel like you've had a cold and are only better for a day or two before feeling ill again, you may have been hit by successive bugs."
In July, The New York Times reported on a similar phenomenon in the US, which experienced a particularly bad summer cold season as pandemic restrictions eased.
Respiratory syncytial virus (RSV), a common illness that is particularly dangerous to infants, has also re-emerged with a vengeance after lockdowns.
RSV cases have surged in Australia, New Zealand, Europe and South Africa.
"RSV and influenza cases dropped dramatically and remained very low throughout winter," the RACGP wrote in May.
Cases remained low until late spring, when a large surge was observed in NSW and Western Australia.
"The speed and magnitude of this increase was greater than the usual winter peak of RSV," the RACGP said.
"More recently, other states including Victoria and Queensland have seen a similar unseasonal rise in RSV cases. It's likely reductions in Covid-19 restrictions have opened the door for increased RSV spread."
By - Frank Chung