@kat1359 I got my first shot on June 18th, by the 23rd I was able to sit and watch tv a lot of the night without oxygen. By the second week I was able to turn my portable oxygen down from 3 to 2 when sitting and still maintain in the mid 90's. Fast forward to now, I still put the portable oxygen on 3 when I am walking, but when I sit down I check O2 and it's usually in the mid to high 90's so I can sit and take it off. But I closely monitor my O2 also. AND I leave the oxygen ON at 1. It takes too long to come back to the level you need if you shut it right off. Hope this helps.