




1. In a study of 124 Beijing households with confirmed cases of SARS-CoV-2 infection, mask use by the index patient and family contacts BEFORE the index patient developed symptoms reduced secondary transmission within the households by 79%. https://pubmed.ncbi.nlm.nih.gov/32467353/
2. Two hair stylists who were COVID-19 positive spent at least 15 min with 139 clients. 67 clients who agreed to be tested were all negative and none of the other clients are known to be infected. Everyone was wearing masks
.
Report: https://bit.ly/2ZrjGD0

Report: https://bit.ly/2ZrjGD0
3. Among more than 1,000 persons interviewed in contact tracing investigations in Thailand, always wearing a mask during high-risk exposures was associated with a reduction in risk of getting infected by 70%, when compared with those who didn't mask. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7588529/
4. Similarly, outbreak aboard the USS
Theodore Roosevelt, where people live and work very closely together found that use of face coverings on-board was associated with a large risk reduction. https://www.cdc.gov/mmwr/volumes/69/wr/mm6923e4.htm?s_cid=mm6923e4_w

5. Contact tracing following a 15 hour international
flight with a symptomatic patient on-board did not turn up any secondary cases. "In our investigation, transmission
may have been mitigated by mild symptoms and masking during the flight" http://www.cmaj.ca/content/192/15/E410.long

may have been mitigated by mild symptoms and masking during the flight" http://www.cmaj.ca/content/192/15/E410.long