[tzs]

That's awfully binary. With SARS-CoV-2 it is a probabilistic thing, where your chances of actually getting an infection depends on how much SARS-CoV-2 you are exposed to and for how long.

Even a cloth or surgical mask does lower that probability. Not enough that it is likely to make a difference if you are going to be exposed for a long time, such as spending hours in room with infected people like might happen at school.

But if you are say going to just do say a quick trip to the grocery store and you only have a surgical mask available, wearing it will lower your chances of getting COVID at the grocery store compared to going maskless.

Some sources: https://www.science.org/doi/10.1126/science.abg6296 , https://www.cdc.gov/mmwr/volumes/71/wr/mm7106e1.htm .

[tinus_hn]

Do note that at least that first source is just people theorizing it should work, not people checking if it actually does work.