That’s because, while we had hoped that recovering from COVID would provide lifetime immunity -- that it would be a “one and done” type of virus, like measles -- that does not seem to be the case.
While we do think there’s immunity for some amount of time for most people after infection with SARS-CoV-2, we still don’t know for sure how immunity works for this particular virus or how long it lasts. Some evidence suggests that a recovered patient’s immunity may fade within weeks or months after infection.
We also know there is a possibility you can get infected more than once with the coronavirus. If that happened, you could be reinfected and not know it -- and if you’re not wearing a mask, you run the risk of spreading the virus to others.
Bottom line: Even if you’ve been infected with the coronavirus, you still should wear a mask in public (when it becomes safe for you to be around other people again).
And remember that masking is only one of the public health practices you should adopt to reduce the spread of this virus. When you’re out, stay at least 6 feet away from other people. Wash your hands frequently or use hand sanitizer regularly. By doing these three simple things, we can prevent more people from becoming sick (maybe more than once) with COVID-19.