"But when Covid pneumonia first strikes, patients don’t feel short of breath, even as their oxygen levels fall. And by the time they do, they have alarmingly low oxygen levels and moderate-to-severe pneumonia (as seen on chest X-rays). Normal oxygen saturation for most persons at sea level is 94 percent to 100 percent; Covid pneumonia patients I saw had oxygen saturations as low as 50 percent."

https://www.nytimes.com/2020/04/20/opini...pgtype=Homepage


Also treatment include laying on side or face down.

FWIW, I have an Innovo Deluxe Fingertip Pulse Oximeter. From what I can tell it works quite well, numbers are consistent with other sensors.

Something else you can add to your self-monitoring routine. Apparently infected people (even those who are asymptomatic) begin to loose their sense of smell early on. A Canadian researcher has suggested that a sniff test of peanut butter, in particular, is a good indicator because of the way the Covid-19 virus affects your smell receptors.
Peanut Butter Sniff Test

If you have problems sensing the complete smell, then you should self-monitor and review other self-testing procedures. If you then show other symptoms, call a physician or you local Covid-19 centre for further instructions to get physically tested.

Smelling the aroma of peanut butter (especially on toast) is one of life's little pleasures for me, but probably not so good for someone who is allergic to nuts.

During the early days (February?) of the pandemic I heard that one simple test was to take a deep breath and hold it for 10 seconds. That alone would supposedly trigger a reaction if your lungs were compromised. Is that “test” still valid or has it been invalidated?

Medical authorities have debunked that one as not having any basis in fact. Some folks with COVID-19 can do that fairly easily especially in the early stages and some folks with unrelated issue often can't do it at all.