Resources:
https://www.kff.org/other/state-indicator/flu-vaccine-requirements-for-health-care-workers-in-hospitals-and-long-term-care-facilities
https://www.cdc.gov/flu/professionals/vaccination/
https://www.cdph.ca.gov/Programs/CID/DCDC/CDPH%20Document%20Library/Immunization/HCWIZRecs.pdf