When people are hospitalised through coronavirus they are faced with just four levels of treatment, with the last two rendering them unconscious.
All treatment options are not designed to cure them of the virus, but simply to support the patient's body as it battles against it.
The patients, now including the Prime Minister Boris Johnson after he was admitted on Sunday night, need oxygen in their blood so it is vital their heart and lungs are properly helped, but each treatment stage becomes more invasive.
Level one treatment sees patients given basic oxygen therapy and is given to people who have become breathless as their oxygen levels in the blood will have fallen.