City of Hope in Duarte, California, has maintained masking requirements, and this has prevented hospital-acquired #COVID19 there entirely, according to Vijay Trisal, MD, chief medical officer at City of Hope.

“Our policies enabled us to achieve zero nosocomial infections, zero outbreaks.”

https://www.cancertherapyadvisor.com/home/cancer-topics/general-oncology/mask-mandates-have-kept-one-cancer-center-free-from-covid-19-others-have-lifted-masking-requirements-despite-patient-concerns/

Mask Mandates Have Kept One Cancer Center Free From COVID-19. Others Have Lifted Masking Requirements Despite Patient Concerns - Cancer Therapy Advisor

Some cancer centers have lifted mask mandates that were intended to protect patients from COVID-19, despite patient concerns.

^{Victoria Forster, PhD (Cancer Therapy Advisor)}