Chaotic scenes of patients being resuscitated on hospital floors and exhausted doctors collapsing onwards are emerging from China amid what has been called a Covid infection “tsunami”.

One video, posted on social media, showed an overrun emergency observation unit at the First Affiliated Hospital of Chongqing Medical University with several patients hooked up to chest compression machines and ventilators strewn around the room.

China had claimed its draconian lockdown policy had kept death rates relatively low but its zero-Covid strategy has now been eased following widespread protests in several cities. Since then, hospitals and fever clinics have been so badly overrun that staff have taken to posting messages online to urge people with mild, manageable symptoms to isolate at home.

Other videos on social media show doctors so exhausted that they are falling asleep while seeing patients.

Dr Wang Guangfa, of Peking University First Hospital, warned that Beijing will see the peak of severe cases within the next two weeks. “The current wave of infection resembles an epidemic tsunami,” he said. He also predicted that northern China will have a higher rate of severe cases than the south because of the cold weather there.

Crematoriums are also under pressure, with one worker in Chongqing reporting they had run out of space to keep bodies.

“The number of bodies picked up in recent days is many times more,” said the man, who did not wish to be named. “We are very busy, there is no more cold storage space for bodies. We are not sure if it’s related to Covid, you need to ask the leaders in charge.”

One crematorium worker in the Zengcheng district of Guangzhou said they were cremating more than 30 bodies a day. “We have bodies assigned to us from other districts. There’s no other option,” the employee said.

Another crematorium in the city reported being “three or four times busier than in previous years. We are cremating more than 40 bodies per day when before it was only a dozen or so,” a member of staff said.

China, so far, has only officially reported a handful of deaths after relaxing its zero-Covid policy. Yesterday, the national health commission said there were five new Covid fatalities, all in Beijing, pushing the country’s overall pandemic death toll to 5,242 — which is relatively low by global standards.

Anecdotal evidence suggests Chinese authorities are under-reporting the number of casualties but the apparent severity of the latest wave of infections means it is also possible that authorities are simply unable to accurately keep track of all deaths and infections, especially as mass testing requirements have been dropped. Some scientific models have estimated numbers will rise.

The US is concerned China’s runaway Covid outbreak could give rise to new mutations of the virus. “When it comes to the current outbreak in China, we want to see this addressed,” a state department spokesman said.

“We know that anytime the virus is spreading in the wild that it has the potential to mutate and to pose a threat to people everywhere.” China is trying to persuade pensioners and other at-risk groups to get inoculated, with only moderate success.

Vaccination centres visited over recent days have been largely empty and there has been no major publicity drive in the state-controlled media. Several regional governments have encouraged people with mild Covid cases to go to work — a sea change from just a few weeks ago when China’s strategy was to isolate anyone infected.