As many as 18,000 nurses have walked off the job and are picketing in front of Northern California Kaiser Permanente facilities.
The two-day strike kicked off Tuesday morning and will last until 7 a.m. Thursday and impact at least 21 Kaiser hospitals and 35 clinics.
Kaiser will remain open during the strike, though some elective procedures and routine appointments may be rescheduled, said company officials.
A California Nurses Association union official said nurses are striking over claims there has been an erosion of patient care standards in Kaiser facilities for months, and that the company has failed to adopt optimal safeguards for Ebola
But California Hospital Association spokeswoman Jan Emerson-Shea said the nurses' union, which is in contract talks, is using the crisis to further its own causes. The association represents and advocates for California hospitals, patients and communities.
But Emerson-Shea said the association is working with federal, state and local agencies to assure the public that widespread precautions are in place to screen and identify infectious diseases. There are no confirmed cases of Ebola in California.
This story has been updated.