[malandrew]

While it may not prevent you from catching the disease, it's pretty much a certainty that it will help mitigate the initial infectious dose you experience if you are exposed. A low initial infectious dose buys your immune system more time to learn to produce antibodies.

[notyourday]

There's no evidence for this to be the case. If we are going to go into "It is common sense to do X" then why stop at "it is a common sense, wear a mask" and not include "It is common sense, if you have co-morbidity then it is you job to self-isolate and let the others to continue to function"