The University of California system’s president announced on Thursday that students, faculty and staff across the university this fall need to be vaccinated against COVID-19 before gaining entry to campuses.

Its recent announcement is a reversal of its plan unveiled in April when the university has only planned to apply the vaccine requirement only if one of the present vaccines is completely approved by the US Food and Drug Administration.

In June, it considered mandated vaccines without FDA approval.

The university, however, did not clear the air of what caused the policy change.

Michael Drake, UC’s systemwide president, laid down the final policy reversal in writing to the 10 chancellors of the university’s campuses. He said the final policy is the fruit of “consultation with UC infectious disease experts and ongoing review of evidence from medical studies concerning the dangerousness of COVID-19 and emerging variants of concern.”

Proof of vaccination must be presented by the students and staff a couple of weeks before the fall term starts, or earlier, the UC policy said.

The fall semester will start next month for UC Berkeley and UC Merced while the other seven undergraduate campuses are set to start the same semester in September.

The proof of vaccination will meanwhile be required for UC staff whose tasks are under the offices that are excluded from the academic calendar, like the system’s president office. Exceptions for religious, medical and disability will be allowed under the policy.

Students, faculty and staff will be required of vaccines if they want to gain access to the campus premises and off-site university programs.

California, in recent weeks, has seen a rise in coronavirus cases driven by the more contagious delta variant, KRON4 reported.

“Vaccination is by far the most effective way to prevent severe disease and death after exposure to the virus and to reduce spread of the disease to those who are not able, or not yet eligible, to receive the vaccine,” the president wrote. The university officials, however, did not give further details regarding the policy change.