The order, issued Thursday by the California Department of Public Health, is different than what Democratic Gov. Gavin Newsom said last month when he announced health care workers would have the choice of either getting vaccinated or submitting to weekly testing.

Now, the order does not give health care workers a choice. It says all must be fully vaccinated by the end of September, with exceptions for people who decline the vaccine because of a religious belief or workers who cannot be inoculated because of a qualifying medical reason backed up by a note signed by a licensed medical professional.

The change comes as California is seeing the fastest increase in new virus cases since the start of the pandemic, averaging 18.3 new cases per 100,000 people a day. Most of the state’s new infections are caused by the delta variant, a more contagious version of the coronavirus that the state says “may cause more severe illness.”

“Increasing numbers of health care workers are among the new positive cases, despite vaccinations being prioritized for this group when vaccines initially became available,” said Dr. Tomás J. Aragón, California’s public health officer. “Recent outbreaks in health care settings have frequently been traced to unvaccinated staff members.”

Gabe Montoya, an EMT at Kaiser Downey Medical Center and a member of the executive committee of the Service Employees International Union-United Healthcare Workers West, said “vaccines are an essential tool in fighting this virus,” adding that “workers must have a voice at the bargaining table whenever new conditions are placed on our work.”

“We’ve put our lives on the line for the last year and a half doing this on a daily basis—at great cost to ourselves and to our families,” Montoya said.

The order represents a new hard line in public health leaders’ quest to convince the hesitant to receive the vaccine. Several states are focusing on health care workers, since they are around vulnerable patients.

But other states with similar requirements have carved out exceptions, like in Oregon, where health care workers can instead get regular COVID-19 testing. In Maryland, the vaccine mandate only applies to certain state employees, such as those who work in health care facilities under the state health department.

In California, vaccine mandates are perilous for Newsom, who is facing a recall election next month fueled in part by anger over his handling of the pandemic. Newsom has angered many parents by continuing to require masks indoors at all public schools, but he has not required all teachers and staff to be vaccinated.

Some California local governments are going beyond the new rule. In Los Angeles County, some 110,000 government workers have until Oct. 1 to be vaccinated under a new order issued by Board of Supervisors Chair Hilda L. Solis.

She noted that about 4 million of the county’s roughly 10 million residents remain unvaccinated. The Los Angeles order doesn’t specify penalties for employees who refuse to be vaccinated.

The city of San Jose in California’s Silicon Valley is also requiring an estimated 8,000 workers to be vaccinated or provide weekly proof of negative COVID-19 tests. It may eventually mandate vaccination, with exemptions for medical or religious reasons.

Meanwhile, a letter to the approximately 5,000 staffers of Los Angeles County Superior Court—the nation’s largest trial court system—ordered them to be fully vaccinated or be fired. The letter says workers must show proof of vaccination no more than 45 days after the federal Food and Drug Administration gives its final approval to one of the vaccines available in the U.S., the Los Angeles Times reported.

Both of those mandates provide exceptions for people on medical or religious reasons.

California’s new vaccine mandate is broad and applies to workers in most health care facilities, including hospitals, skilled nursing facilities, psychiatric hospitals, adult day health care centers, dialysis centers, hospice facilities and clinics and doctor’s offices.

Carmela Coyle, president and CEO of the California Hospital Association, called the vaccine mandate “an important step in the long battle we face against COVID-19 and the multiple variants that have emerged.”

“We are once again on a dangerous precipice that demands both our fortitude and our goodwill to protect loved ones and neighbors,” Coyle said. “California’s health care workers are being called upon—as they have through every step of this pandemic—to lead the charge in the battle between vaccine and variant.”

In a separate order, the state required hospitals, skilled nursing facilities and intermediate care facilities to verify all visitors have either been vaccinated or tested negative for COVID-19 at least three days before an indoor visit. The state said it would give its updated guidance for long-term care facilities “in the near future.”