Add finger pulse oximeters to the list of things that have become suddenly scarce during the coronavirus pandemic, which has already changed our lives in myriad ways. Concerned consumers have been snapping them up, convinced that regular monitoring of their blood oxygen levels can detect silent hypoxia, a symptom of COVID-19. Although this sudden drop in the amount of oxygen in your bloodstream can indicate a coronavirus infection, the American Lung Association says this symptom usually doesn't manifest until an infected person has already become seriously ill. Fever, dry cough, muscle aches, and fatigue are much more common early indicators of COVID-19. Still, there can be peace of mind in knowing you're prepared in case you do get sick — you'll have a way to monitor your condition. Here are some recommended pulse oximeters and a few things to understand before buying.