All California State University campuses, which includes Fresno State, will require students, faculty and staff to be vaccinated against COVID-19 — possibly as early as the fall semester.

The 10-campus CSU system joined with the 23-campus University of California system in announcing the vaccination requirement on Thursday. The plan is most expansive in American higher education.

“Together, the CSU and UC enroll and employ more than one million students and employees across 33 major university campuses, so this is the most comprehensive and consequential university plan for COVID-19 vaccines in the country,” CSU Chancellor Joseph I. Castro said in the statement.

UC and CSU Schools to Require Vaccinations

Several U.S. colleges and universities also have said they plan to require the vaccination. Stanford University also announced a mandate Thursday requiring all of its 19,000 students to be vaccinated when classes start in the fall.

Timing of Mandate Pending on FDA Authorization

The Pfizer and Moderna vaccines are being distributed under the Food and Drug Administration’s emergency authorization. Health experts expect formal approval of at least one by the fall. The Johnson & Johnson vaccine is on pause due to concerns about blood clots.

CSU spokeswoman Toni Molle said the timing of a formal mandate will depend on when the FDA gives full authorization to one or more of the vaccines and also on discussions with labor unions. It could come before classes start or after.

“We are announcing now so that students and employees have time to receive a vaccination in the event that we have implemented a requirement,” she said.

Students who have an approved exemption for medical or religious reasons will be required to undergo regular COVID-19 testing.