The company cited flu season, the spread of the COVID-19 Delta variant, and the high hospitalization rate among unvaccinated as reasons for the requirement.
Reporters spoke with loved ones of healthcare workers across the country have risked their lives to care for COVID-19 patients.
Health experts worry that with widespread surges of the virus happening nationwide, there won't be enough healthcare workers to go around.
Phoenix doctor and state Rep. Amish Shah was one of the volunteers who participated in the clinical trials for the Pfizer vaccine in August.
The Arizona Hospital and Healthcare Association has estimated that hospital revenues are down 30-40% due to fewer surgeries and emergency room visits.