No one has done a controlled study on this, so no one really knows. It ranges from zero to many.
The reason government and medical signaling on the subject has been so mixed is that it isn’t apparent they are very effective, especially the jury rigged cloth masks that people are using.
The reason government and medical signaling on the subject has been so mixed is that it isn’t apparent they are very effective, especially the jury rigged cloth masks that people are using.