Norovirus has forced hospitals in England to close 1,100 beds in just one week - with one facility shutting down four wards to prevent the virus from spreading.
New data from Public Health England (PHE) said the number of norovirus laboratory reports for November 11 to 24 was 28 percent higher than the average for the same period in the previous five years.
Double the number of hospital beds have also been closed every day over the last week than at the same time last year, while trusts try to stop the bug spreading between patients.
The illness - sometimes referred to as the "winter vomiting bug" - causes vomiting and diarrhoea among patients of all ages.
A school was forced to shut its doors after more than 100 pupils became bedridden with the virus.
One hospital - the Royal Berkshire in Reading - has closed four wards, confirming six patients had tested positive for the bug, while a further five cases are currently being investigated.
As such, NHS England is advising people to stay at home for 48 hours if they get the bug to avoid passing it on.
NHS medical director, Professor Stephen Powis said: “We’ve already seen a number of hospitals and schools affected by norovirus, and unfortunately instances like these are likely to rise over the coming weeks.
“It’s a really unpleasant illness to catch, but for the vast majority of people it will usually pass in a couple of days, and self-treating at home is the best way to help yourself and avoid putting others at risk.
Read more from Yahoo News UK:
Pensioner left lying on wet ground for three hours waiting for an ambulance
Corbyn frames election as 'fight for NHS' with 'proof' of US Brexit deal talks
The 360: Who can you trust to take care of the NHS?
“Crucially, if you’re experiencing norovirus symptoms it’s important that you don’t return to work or school for 48 hours after they clear – and avoid visiting elderly or ill friends and relatives – to avoid spreading it to other people.”
People with concerns are advised to stay at home and contact NHS 111 or talk to their GP by phone.
It is estimated that between 600,000 and one million people in the UK become infected each year.
About 12 to 48 hours after becoming infected, the virus causes sudden onset of nausea followed by vomiting and diarrhoea.
Meanwhile, a branch of Wetherspoons in Lancaster - The Sir Richard Owen - has been closed until further notice following a norovirus outbreak.