The mask debate was an intelligence test. If you have any friends who argued that masks don’t work, you can confidently place them on the lower end of the intelligence bell curve.
Excerpt.
Coronavirus Diagnoses In Staff Drop By Half After Boston Hospital Requires Masks For All
New infections diagnosed in Brigham and Women’s employees dropped from 12 or 14 a day to more like eight once they all had to wear masks, and to about six once patients had to wear masks as well.
https://www.wbur.org/commonhealth/2020/04/23/brigham-and-womens-masks-infections