A federal judge on Monday issued a preliminary injunction halting the implementation in several states of a Biden administration COVID-19 vaccine mandate for millions of health care workers.

The ruling by Matthew T. Schelp, a U.S. district court judge for the Eastern District of Missouri, Eastern Division in St. Louis, lists a range of reasons why the mandate, which was issued earlier this month, likely won’t be enforceable.

The case, State of Missouri et al. v. Joseph R. Biden Jr., which was brought by 10 states, centers on the Medicare and Medicaid Program; Omnibus COVID-19 Health Care Staff Vaccination regulation issued by the Centers for Medicare & Medicaid Services on Nov. 5. The suit is one of several challenges to vaccine mandates. 

The mandate requires that staff at facilities participating in Medicare and Medicaid programs – about 17 million workers – have at least one dose of a vaccine by Dec. 6 and be fully vaccinated by Jan. 4, 2022.

According to the ruling, the states will likely succeed in their arguments in a full hearing that: Congress did not grant CMS authority to mandate the vaccine; CMS unlawfully bypassed notice and comment requirements; and the mandate is “arbitrary and capricious” because, among other things, “CMS lacks evidence showing that vaccination status has a direct impact on spreading COVID in the mandate’s covered health care facilities” and it rejected alternatives such as regular testing.

In addition, the mandate will impose irreparable harm on the states, such as exacerbating health care staff shortages and the cost of implementing the mandate, the ruling states.

“Because it is evident CMS significantly understates the burden that its mandate would impose on the ability of health care facilities to provide proper care, and thus, save lives, the public has an interest in maintaining the ‘the status quo’ while merits of the case are determined,” the ruling stated.

In addition to Missouri, the preliminary injunction applies in Alaska, Arkansas, Iowa, Kansas, Nebraska, New Hampshire, North Dakota, South Dakota and Wyoming.

The ruling is another blow to President Biden’s efforts to impose vaccine mandates. Earlier this month, to comply with a federal appeals court ruling, the Occupation Safety and Health Administration suspended activities related to its emergency temporary standard mandating COVID-19 vaccines or regular testing for millions of workers.

Workers at various companies have also sued to stop vaccine mandates imposed by private employers. Earlier this month, The Walt Disney Co. paused its mandate in Florida after state lawmakers banned compulsory shots.