This interim final rule with comment period revises the requirements that most Medicare- and Medicaid-certified providers and suppliers must meet to participate in the Medicare and Medicaid programs. These changes are necessary to help protect the health and safety of residents, clients, patients, PACE participants, and staff, and reflect lessons learned to date as a result of the COVID-19 public health emergency. The revisions to the requirements establish COVID-19 vaccination requirements for staff at the included Medicare- and Medicaid-certified providers and suppliers.