I fallet Boris Johnson:
https://www.wsj.com/articles/inside-boris-johnsons-brush-with-covid-19-11589552162
"On
March 26, Mr. Johnson stood outside Downing Street to join a nationwide applause for hospital workers, but he was feeling unwell. Britain’s chief medical officer had advised him to get a test for Covid-19. At midnight he received the result:
positive.
A week after his diagnosis, although Mr. Johnson wasn’t gasping to breathe, his doctors grew concerned that the level of oxygen saturation in his blood was too low.
At 8 p.m. on Sunday,
April 5, as Queen Elizabeth rallied the nation with a televised address, an aide drove Mr. Johnson south across the Thames to St Thomas’ hospital. Inside the concrete tower he was placed on a general ward on the 12th floor and given oxygen through a tube in his nose, and then through a mask.
On Monday,
April 6, which was 11 days after Mr. Johnson’s positive test, his condition deteriorated. A monitor showed his blood oxygen slipping. Within hours, the situation became grave and the ICU prepared for his arrival.
He had aching muscles, a sign of oxygen starvation, which can cause rapid damage to the body. But ventilation can result in harm, too, with the harsh process of forcing oxygen into a the lungs and the heavy sedation required."