SACRAMENTO, Calif. (NEXSTAR) — California will require all of its roughly 2.2 million health care and long-term care workers to be fully vaccinated against the coronavirus by Sept. 30.

Democratic Gov. Gavin Newsom said last month he would require health care workers to either be vaccinated or submit to weekly testing. But the new order issued Thursday by the California Department of Public Health does not give health care workers a choice.

It says all must be fully vaccinated by the end of September. California is averaging 18.3 new coronavirus cases per 100,000 people per day.

The delta variant is causing most of the new infections.

“California is currently experiencing the fastest increase in COVID-19 cases during the entire pandemic with 18.3 new cases per 100,000 people per day, with case rates increasing ninefold within two months,” the order from the California Department of Public Health states. “The Delta variant is highly transmissible and may cause more severe illness. In fact, recent data suggests that viral load is roughly 1,000 times higher in people infected with the Delta variant than those infected with the original coronavirus strain, according to a recent study.”

Currently, 63% of Californians ages 12 and older have been fully vaccinated, with another 10% partially vaccinated, according to health department statistics.

As of Thursday afternoon, California had tallied 64,620 COVID-19 deaths and 4,003,787 cases since the start of the pandemic, according to Johns Hopkins data.

The Associated Press contributed to this report.