I'm not sure if I can convey, in words, what it feels like to take care of a dead man walking.
Just another day in the ICU. He was around 70 years old. A pretty active guy, one of those relatively stubborn and fiercely independent people who didn’t typically go to the doctor unless their arm had been ripped off. He had come to the hospital a couple of days ago with a cough, fever, and a little trouble breathing. Unsurprisingly, he had COVID-19. It turns out that his saturation percentage of arterial capillary oxygen (SpO2) was around 60% when he hit the doors of the emergency department.
Off onto a rabbit trail physiology lesson for a minute: in our blood, there is a protein called hemoglobin. Each single hemoglobin protein is capable of carrying 4 oxygen molecules at a time. If they are carrying 4, then they are “saturated” with oxygen. The hemoglobin molecules pick up oxygen molecules in the lungs, carry them to the body’s tissues, drop them off, and then return back to the lungs to grab more oxygen. The body tissues need this oxygen in order to stay alive. The oxygen saturation number, or SpO2, measures what percent of the hemoglobin molecules that are flowing past the sensor are saturated with 4 molecules of oxygen. Normal SpO2 is 94-99%. If the saturation is less than that, some of the tissues cannot get enough oxygen to stay alive, and are forced to start essentially eating themselves. One of the classic signs of significant COVID-19 illness is having a SpO2 level that is alarmingly low, with only moderate symptoms.
Back to the patient: let’s call him “Bob.” When I walked on the floor of ICU to get report that morning, Bob had been transferred there a few hours before because they couldn’t keep his SpO2 above 88% on the regular nursing floor in spite of increasing his oxygen supply dramatically.
The night shift nurse described how Bob was taking off his oxygen to scratch his nose, and taking off his SpO2 sensor because it was irritating his finger. She kept reminding him to put his high flow nasal cannula back into his nose, and had to replace the oxygen sensor several times. She finally had a frank and confrontational conversation with him.
https://www.reddit.com/r/nursing/comments/rwo7ib/another_covid19_bedside_story/
= new reply since forum marked as read
of why, and what will most likely happen if they don't. I've had to explain to people that they have the choice to do something or not. If they choose not to, let's call their kids home so they can be there when they die.
The response? "Oh. The doctor didn't tell me that."
I couldn't be working ICU now. 
I consider myself lucky, my brother isn't anti-vaxx, I managed to get him vaccinated back in April and May. His issue is that he's agoraphobic, doesn't like to leave the house. When the vaccination site at the nearby local mall started accepting walk-ins last Spring, I convinced him to go, took him myself. But he was resistant to getting a booster, I tried to convince him, but he kept asking how many more he had to get. However, he had to go out to get his prescription refilled and noticed they were accepting walk-ins at the mall again, so he stopped and got his booster at the same place. He met me at the door and showed me his card, I think he's now proud he did it. I sure hope that your sister learns something that convinces her, things have gotten bad enough that Covid is everywhere.
And welcome to DU, you're among like minded friends here. 
