There are no rules in effect. Companies are reacting to possible regulations coming from OSHA, which if issued, will be challenged, and litigated all the way to the Supreme Court on an expedited basis.
The details of Biden’s emergency regulation, which will come from the Department of Labor’s Occupational Safety and Health Administration and applies to private employers with 100 or more workers, haven’t been developed yet.
Meanwhile, private companies with more than 100 employees will be subject to a forthcoming rule from the Occupational Safety and Health Administration requiring all employees to be vaccinated or get tested weekly. Biden announced the regulation weeks ago, but the agency is still drafting the particulars.