Video: UK Prime Minister Boris Johnson risked dying during COVID-19 treatment

UK Prime Minister Boris Johnson praised doctors for saving his life during his week-long hospitalisation for COVID-19 treatment that has left him too weakened to resume immediate leadership of the government.

Looking pale and gaunt, the premier thanked the National Health Service for the care he had received. In a 5-minute video posted on Twitter on Sunday, he called the health service "unbeatable," and lauded the "personal courage" of the doctors, nurses, cleaners and cooks who work for it.

"The NHS has saved my life, no question; it's hard to find words to express my debt," the premier said, his voice still croaky. He thanked the staff who cared for him, including "two nurses who stood by my bedside for 48 hours when things could have gone either way."

Johnson won't return to work right away, instead continuing his recovery at his official country residence, Chequers, his office said. In his absence, Foreign Secretary Dominic Raab has been deputizing, while emphasizing that decisions are being made by the cabinet as a whole.

Meanwhile, the government said in a statement that Parliament will resume activity on April 21. House of Commons authorities will consider how to use technology to best allow lawmakers to fulfill "essential constitutional functions of conducting scrutiny, authorizing spending and making laws," the government said on Sunday.

UK death toll crosses 10,000

Despite the developments, the U.K. is far from returning to normality. After three weeks of lockdown that's brought large swathes of the economy to a standstill, government scientists still aren't confident the pandemic has peaked. The death toll rose by 737, surpassing 10,000 on Sunday, making Britain the fifth country to cross that grim threshold.

"The U.K. is likely to be certainly one of the worst, if not the worst affected country in Europe," Jeremy Farrar, a member of the scientific panel advising the government on the pandemic, told the BBC.

Health Secretary Matt Hancock called the death-toll landmark "somber" and said comments like Farrar's show the need for the public to keep its discipline in observing social-distancing rules.

"The future of this virus is unknowable as yet because it depends upon the behavior of millions of people," Hancock said in a televised press conference. "The good news is that so far we have managed to start to see a flattening of the curve because people are following the social-distancing measures."

Hancock also said the NHS is preparing to launch a contact-tracing app that can be used to tell other app-users if someone they've been physically near tests positive for the virus.

Johnson's treatment

Johnson was taken to the hospital last Sunday after failing to shake off the virus-related cough and fever he'd been suffering from for 10 days. He was put into intensive care the following day and was given oxygen to help with his breathing. He remained there until Thursday before being transferred back to an ordinary ward, where a day later, his office indicated he could take short walks.

The seriousness of Johnson's condition was reflected in social media posts Sunday by his partner Carrie Symonds, and by his own video message.

Johnson named many of the staff who cared for him at St. Thomas' Hospital in central London, picking out nurses called Jenny from New Zealand and Luis from Portugal in particular.

"The reason in the end my body did start to get enough oxygen was because for every second of the night, they were watching, and they were thinking, caring and making the interventions I needed," Johnson said.

There was also a flash of Johnson's trademark humor when he thanked his doctors "men and women, but several of them for some reason called Nick." They had, he said, made "crucial decisions a few days ago which I will be grateful for for the rest of my life."

The most severe cases of the virus can take weeks to recover from, and Johnson's office gave no indication of when he might be back at work. Hancock said when Johnson returns is a "clinical decision" for the premier's doctors to take, and that there hasn't yet been any guidance on how long it might be.

Equipment Shortfall

Johnson's administration has come under increasing criticism from the opposition and by U.K. media over the time it took to respond to the pandemic, the level of testing for the virus and the amount of vital protective equipment - known as PPE - reaching hospital and care home staff.

Attention has focused on getting aprons, gloves and face masks to hospital workers and nursing home staff. Sharma told Sky nurses "shouldn't be placed in that position" of lacking protective gear, before saying on the BBC he was "incredibly sorry that people feel they have not been able to get this equipment."

According to Hancock, it's "impossible" to say when deliveries would match what's needed.

"The quest is to get the right PPE to the right people on the front line at the right time," he said. "Until everybody gets the PPE that they need, then we won't rest."