Many of California’s 2.5 million health care workers will be among the first Americans who can get COVID-19 booster shots, after the U.S. Centers for Disease Control and Prevention decided early Friday to recommend a third Pfizer dose for them and other high-risk groups.

The development followed an unusual but brief moment of disagreement between vaccine advisers at the CDC and the Food and Drug Administration, the two federal agencies that set U.S. COVID vaccine policy.

Ultimately, both the FDA and the CDC agreed to endorse boosters for people 65 and older, nursing home residents, adults with underlying conditions, and adults who live or work in settings that put them at high risk of exposure or transmission. Friday afternoon, the Western States Scientific Safety Review Group — scientists in California, Washington, Oregon and Nevada — aligned with the CDC’s recommendations, opening the door for Californians in those groups to officially seek boosters.

But the path to endorsement this week had been bumpy.