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SACRAMENTO, Calif. (KTXL) — California’s requirements for events with large crowds went into effect Monday.

Anyone who wants to go to an indoor event with 1,000 or more attendees will need to provide proof of vaccination or a negative COVID-19 test, which they will need to get no earlier than 72 hours before the event.

“The Delta variant has proven to be highly transmissible, making it easier to spread in large crowds where people are near each other for long periods of time,” Dr. Tomás J. Aragón, director of the California Department of Public Health and state public health officer, wrote last month when the requirements were announced. 

That means “self-attestation to verify a person’s vaccination status will no longer be accepted,” according to health officials. 

Many venues and events across the state adopted the requirements well before the Sept. 20 start date.

The requirement is expected to be in place until Nov. 1. 

More than 23 million Californians, or just over 69% of the state’s population, are fully vaccinated.