While vaccines have proven to stop the spread of the virus — and groups such as the ACLU support mandates — the actual rollout is causing concern for employers who want a less strict alternative to avoid shutdowns.

“The major employers we’re talking to across all sectors of the economy are trying to do the right thing and be very strong advocates to get vaccinated," California Business Roundtable President Rob Lapsley said. "But if we don’t have flexibility, people aren’t going to go along with the program, and we can't lose workers, especially right now in this economy,”

School officials are the latest to demand a way around California’s Covid-19 vaccine requirements. Newsom last month announced the nation’s first Covid vaccine mandate for students to attend class. He ordered the same for teachers earlier this fall.

Though implementation of the student mandate is still months away, pending full FDA authorization of shots for kids under 16, a growing number of school superintendents are pleading with Newsom and state lawmakers to ensure students can opt out through a “personal exemption,” a waiver that does not exist for other childhood vaccines in the state. Exemptions are currently allowed under Newsom's rule, but the state Legislature could soon change that.

“If students’ parents are forced to make a choice next summer, we believe we will have a much larger group of students remain outside our school systems,” Merced County Superintendent of Schools Steve Tietjen said in a Wednesday email to educators obtained by POLITICO. “No matter what I think about the importance of the vaccination, and its ability to keep people safe, we need to keep our students in school.”

Tietjen and other California school officials are worried that high numbers of students — many of whom qualify as low-income — will remain unvaccinated and thus be moved to distance learning programs that are understaffed and subpar to classrooms. The state has a teacher shortage exacerbated by the pandemic, and districts are finding they are ill-equipped to run traditional school offerings alongside a separate remote learning track.

School leaders and community activists are also concerned about pushing Black and Latino students out of classrooms, since vaccination rates remain lower in communities of color.

Newsom won praise for issuing the first vaccine-or-test requirements for state employees this summer as leaders in red states fought against Covid mitigations. “As the state’s largest employer, we are leading by example and requiring all state and health care workers to show proof of vaccination or be tested regularly, and we are encouraging local governments and businesses to do the same,” Newsom said then. “Vaccines are the way we end this pandemic.”

But state agencies have since failed to test roughly half of unvaccinated employees — and allowed them to keep working, according to a report last month by the Los Angeles Times.

“The governor's office has led this, and clearly even they have had challenges,” Lapsley said. “It all comes back to flexibility."

Meanwhile, state officials are adamant that they cannot run prisons if staff is required to get vaccinated, as correctional officers are more opposed to vaccines than the general public despite multiple outbreaks in the close quarters. The officers’ union has found an ally in Newsom, who has fought prison advocates in court seeking to force immunizations rather than a vaccine-or-test option, warning that it will lead to significant staffing shortages in the prison system because of low vaccination rates.

The stance is so out of character for Newsom — who has been among the nation’s most aggressive on vaccinations — that Republicans have accused him of siding with correctional officers because they gave him $1.75 million to defeat the September recall.

“It’s inexplicable to me for a governor, who has been doing much to protect the lives of all Californians, to fight so hard against the most effective way to prevent more deaths and illness in the prison system,” Donald Specter, executive director of the Prison Law Office, which is representing plaintiffs in the case against the state, told POLITICO last month.

The concerns about the impact vaccine mandates can have on staffing and capacity are echoed by other industries.

The U.S. Postal Service has already said the mandates could lead to "high levels of absenteeism" and affect deliveries.

The Western Steel Council, which represents ironworkers, urged the California Occupational Health and Safety Administration to allow more flexible rules. Greg McClelland, executive director of the Western Steel Council said in a letter last week to state officials, that a mandate will subject employers to a “rigid” rulemaking process that sometimes defies common sense.

“Many of us were far ahead of the enforcers in digesting and following the advice of the experts on how to protect against the spread of COVID. And as the advice continued to evolve, we continued to change our procedures to keep pace with the changing advice,” the letter states.

California OSHA officials have since stalled their plan to move forward with a vaccine-or-test mandate for private employers. The Cal/OSHA Standards Board abruptly removed the item from its Thursday agenda, and board members declined to discuss the issue after the U.S. Department of Labor advised states to “take no further steps to implement” the federal requirement as the Biden administration remains tied up in court.