Someone posted a letter from a doctor to his patients on FB. He said that the virus alone will filter through just about any mask, but they need a particle or droplet to carry them. The N95, N100, or P95, P100 masks will filter out the smaller particles or droplets. I ordered some N95 masks through Amazon last week. They came today, a box of 25. Probably not nearly enough if this goes on for a while.
25 masks are only good for one use or one per day/outing.