The U.S. Supreme Court will not block Maine’s COVID-19 vaccine mandate for health care workers while a legal challenge proceeds.

Nine unnamed workers sued the state in August to demand a religious exemption to that rule. Last week, federal judges in the U.S. District Court of Maine and the 1st U.S. Circuit Court of Appeals in Boston both declined to stop the mandate from taking effect while the lawsuit is heard. So the plaintiffs asked the nation’s highest court for that emergency relief, and Associate Justice Stephen Breyer denied that application Tuesday.

Health care workers needed to get their shot by Friday to be in compliance with the rule by the end of October, when Gov. Janet Mills has said she will start enforcing the mandate. A person who gets the Johnson & Johnson shot is fully vaccinated two weeks later.

The court’s decision does not end the lawsuit. The 1st Circuit is still considering the underlying case. Breyer said the plaintiffs could try again at the Supreme Court after the 1st Circuit issues an order, or if the appeals court does not issue such a ruling by Oct. 29.

It was the first time the Supreme Court addressed a statewide vaccine mandate. Individual justices have similarly denied requests for emergency relief from vaccine mandates by New York City teachers and Indiana University staff and students.

A spokesman for the Maine Attorney General’s Office declined to comment on that decision.

“Justice Breyer’s decision speaks for itself,” Marc Malon wrote in an email. “The case remains in the 1st Circuit.”

Liberty Counsel, the conservative group that represents the plaintiffs, said in a news release that the decision still “leaves the door open” for Maine health care workers.

“We are pleased that the Supreme Court is ready to consider this case if we do not get relief at the 1st Circuit Court of Appeals or if the lower court does not rule by October 29,” Mat Staver, the founder and chairman, said in the release. “As of Monday, our case is now fully briefed at the court of appeals. We look forward to an expedited ruling. There is no question that Gov. Janet Mills cannot nullify federal law and the First Amendment to the U.S. Constitution.”

In Maine, the governor’s office has estimated that the mandate will apply to more than 150,000 workers at hospitals, clinics, group and nursing homes, dental offices, EMS agencies and other state-licensed health care facilities. The state published data last week that showed COVID-19 vaccination rates increased in September among Maine health care workers, surpassing 91 percent in hospitals and 85 percent in nursing homes.

The case tests the state law that repealed religious or philosophical exemptions for required inoculations for students and health care workers. The Legislature decided in 2019 that only medical exemptions would be allowed for those shots, and that change survived a referendum challenge the following year. This year, Mills added the COVID-19 vaccine to those already required for health care workers, which include shots against chicken pox and the common flu.

If the case does return to the Supreme Court, those interested in the conservative shift on the bench will be watching it closely. The justices have recently signaled a greater sympathy to religious liberty arguments like the one made in this lawsuit.

Liberty Counsel, the conservative group that represents the plaintiffs, says the health care workers’ objections are rooted in scripture and in a rejection of any medicine or procedure developed with or aided by the use of fetal tissue. They argued that Maine needs to offer a religious exemption because it offers a medical one. The rule treats people who seek a religious exemption less favorably, they said, and therefore violates their right to freely practice their religion.

The state argued that the two types of exemptions aren’t comparable and shouldn’t be viewed in the same way under the law. Maine stopped accepting religious and philosophical exemptions to all mandatory vaccines in order to protect people who could not get those shots because of their medical conditions. The Attorney General’s Office said that reasoning still applies during the COVID-19 pandemic.

U.S. District Judge Jon Levy agreed with the state when he issued his order last week.

“Reducing the risk of adverse medical consequences for a high-risk segment of the population is essential to achieving the public health objective of the vaccine mandate,” he wrote. “A religious exemption would not address a risk associated with the vaccine mandate’s central objectives.”

The 1st Circuit set an expedited schedule and will decide the case based on briefs. The parties filed the written arguments by the deadline Monday.