Masks don’t prevent you from getting it but protect others from getting it from you, if you have symptoms stay home
That's not what the AHA told hospital workers. They told them that if you were wearing a gouwn and gloves without a mask and goggles that your risk of exposure was high.
But if you were wearing a mask and goggles even if you didn't have a gown or gloves on, your risk of exposure was low.
The virus infects you through moist membranes. It has to find a body opoening. It can't infect you through skin. Although if you get it on your hands and then touch your face, it can infect you. Thus the wash your hands and don't touch your face, commands.
They realized they didn't have enough gear for the healthcare workers, so they told people it wouldn't protect them, because they didn't want people buying masks when they needed them for healthcare workers.