The UK is experiencing its worst outbreak of flu in seven years, the Department of Health and Social Care has revealed.
A department spokesman has described it as "the most significant flu season since the winter of 2010-11", with thousands more people being treated in December than during the same month in 2016.
"We know hospitals are under pressure and hardworking staff treated 55,328 people within four hours every single day in December - 1,272 more each day than in the same month the previous year," they added.
"We have supported the NHS this winter with an additional £437m, and made the free flu vaccination available to 21 million people - 700,000 more than last year."
Earlier on Thursday, the director of policy and strategy at NHS Providers, which represents hospitals and ambulance trusts, said the impact of flu remained a "serious concern", despite hospital bed occupancy rates easing slightly in the last week.
"The worst of winter may be yet to come," he warned.
Public Health England is continuing to urge people at risk of flu to book a free vaccination, and those with severe symptoms are being told to stay at home and rest until they get better.
Official advice is for those suffering to "catch" any sneezes in a tissue, "bin" the tissue immediately, and "kill" the virus by washing their hands with soap and warm water afterwards.