The U.S. federal government's efforts to encourage widespread vaccination against COVID-19 have been challenged by some officials and experts, particularly since its vaccine mandate was formally introduced to large-scale businesses on Thursday.

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The vaccination rule came as many communities are still struggling with limited health care staff and resources to help those who are currently battling COVID-19. The White House insisted the measures mean common good for the country and will be upheld no matter what the costs will be.

Major blow

Three judges from the U.S. Court of Appeals for the Fifth Circuit who were appointed by Republican presidents ruled on Saturday to temporarily halt a mandate by President Joe Biden's administration that required employees of large companies to get vaccinated or undergo frequent testing.

The mandate requires employees of companies with a workforce of 100 or more to get fully vaccinated by Jan. 4 next year. Unvaccinated ones must submit weekly negative COVID-19 tests to enter the workplace after the deadline, and have to wear masks indoors at their workplaces starting Dec. 5 this year.

The order by the court said "there are grave statutory and constitutional issues with the mandate" and suspended the mandate "pending further action by this court." This order has delivered "a major blow for one of the White House's signature attempts to increase the number of vaccinations to corral the pandemic," reported The Washington Post.

The Labor Department's top legal advisor said the administration was confident in its authority to issue the mandate and fully prepared to defend the rules. The mandate will be enforced by the Occupational Safety and Health Administration (OSHA), whose lawyer said it has the authority "to act quickly in an emergency where the agency finds that workers are subjected to a grave danger and a new standard is necessary to protect them."

A total of 223,245,121 people have received at least one COVID-19 vaccine dose, making up 67.2 percent of the whole U.S. population. Fully vaccinated people stood at 193,627,929, accounting for 58.3 percent of the total, the Center for Disease Control and Prevention updated on Sunday.

Party Backlash

Republican Florida Governor Ron DeSantis has joined several other state officials in announcing plans to sue the administration over the new mandate.

"We started with 15 days to slow the spread and now it's get jabbed or lose your job," DeSantis said, adding that "there is no federal police power and the federal government cannot unilaterally impose medical policy under the guise of workplace regulation."

Florida has banned counties from forcing their employees to get vaccinated, and school districts from universally enforcing mask mandates among students. Republican officials from several other states have also announced plans to combat the mandate. Texas Attorney General Ken Paxton will announce his plan to sue "once this illegal, unconstitutional regulation hits the Federal Register." Even Democratic Kansas Governor Laura Kelly came out against Biden's vaccine mandate, saying it is not the "most effective" or "correct" one for her state.

"Yesterday, I reviewed the new vaccine mandate from the Biden Administration. While I appreciate the intention to keep people safe, a goal I share, I don't believe this directive is the correct, or the most effective, solution for Kansas," she said, stressing that "It is too late to impose a federal standard now that we have already developed systems and strategies that are tailored for our specific needs."

Debate from within

The debate over mandatory vaccination policies even surfaced in the National Institutes of Health (NIH), a federal research agency that has led government efforts studying and battling COVID-19. The agency's main bioethics department has scheduled for Dec. 1 a live-streamed roundtable session over the ethics of the mandate. The seminar is one of four agency-wide ethics debates this year, accessible to all of the NIH's nearly 20,000 staffers, as well as patients and the public, organizers say.

"There's a lot of debate within the NIH about whether (a vaccine mandate) is appropriate," said David Wendler, a senior NIH bioethicist who is in charge of planning the session.

Matthew Memoli, who runs a clinical studies unit within the NIH's National Institute of Allergy and Infectious Diseases, will make the case against the mandate at the roundtable session. He opposes mandatory COVID-19 vaccination with currently available shots. "I think the way we are using the vaccines is wrong," he said.