The United States Supreme Court in National Federation of Independent Business v. Department of Labor, rejected a mandate requiring employers with more than 100 employees to require their employees to vaccinate or test, holding that there was no clear congressional authority under OSHA. The Court made it clear that in order to require such a far sweeping employer mandate it would be necessary for Congress to act. However, the Court upheld in Biden v. Missouri, the requirement that the Administration health care workers at facilities that receive federal funds could continue to enforce a vaccinate mandate for health care workers. National Federation of Independent Business v. Department of Labor and Biden v. Missouri, (SCOTUS 21A240 21A241, 1/13/22)
For a detailed analysis see Amy Howe, Scotusblog (SCOTUS 21A244, 1/13/22)
Comment Howard: Local governing bodies for home rule cities and counties have the power to enact public health mandates unless denied by their charter. Otherwise, legislative authority from the Missouri legislature seems to be required under National Federation of Independent Business v. Department of Labor for statutory cities and counties. For third class cities, Missouri has provided legislative authority to enact public health mandates in Section 77.530. You may want to check to see if section 77.530 is replicated in other statutes.