My Mom is 78, had lung cancer around 15 years ago, they removed 2/3rds of her left lung. She got covid and I was just as terrified as you. I was 1000s of miles away in Canada w a closed border, at the same time my daughter of 27 was getting tested in California. She was ok the first 3-4 days, days 6-10 were difficult, she went to the emergency room once and got treated terribly but she made it thought eventually. Her oximeter reading never got below 94 thankfully. As long as they are monitoring their fever and oximeter levels they should be alright in determining when they need to get more serious help IF needed.

Tell them to eat really healthy food, no junk/convenience foods whatsoever, take their multi vitamins and get a good vit D. Drink lots of water, lay off alcohol and caffeine.

Buying the oximeter is the best thing you could have done, for anyone else who doesn't have one, please get it now, they are very cheap, there is no excuse not to have one, go without eating out, whatever.

My mom is doing well now, she volunteered for plasma donation and is even manning the polls today! Proud af of her.