Los Angeles’ sweeping new vaccine mandate goes into effect Monday, which requires proof of vaccination in order for patrons to enter most public indoor spaces in the second most populous city in the U.S.

Believed to be among the most far-reaching vaccination requirements in the nation, the ordinance from the Los Angeles City Council was signed by Mayor Eric Garcetti in October but took effect Monday morning, covering everyone who is eligible for a coronavirus vaccine (or people ages 12 and up).

The mandate requires proof of vaccination to enter the indoor portions of any establishment where food or beverages are served (such as restaurants, bars, coffee shops, etc), gyms and fitness venues, entertainment and recreation venues (including movie theaters, music and concert venues, museums and shopping centers), personal care establishments (like spas and nail salons), and any facilities or buildings owned or operated by the City of Los Angeles.

It will also require proof of vaccination for large outdoor events with 5,000 or more attendees.

To demonstrate proof of vaccination, people can use their CDC-issued vaccination card or a similar document issued by a foreign government agency, a photo of both sides of their vaccination card, documentation of vaccination from a licensed health care provider or a personal digital COVID-19 vaccine record issued by the State of California or similar entities (such as the State of California’s Digital COVID-19 Vaccine Record, which can be downloaded onto a smartphone and show proof of vaccine via a QR code).

The mandate has exemptions for those who are not vaccinated due to a medical condition or religious belief, but still requires those individuals to have proof of a negative COVID-19 test that was administered within 72 hours prior to seeking entry to an indoor facility or large outdoor event.

“Vaccinating more Angelenos is our only way out of this pandemic, and we must do everything in our power to keep pushing those numbers up,” Garcetti said in a statement last month when he signed the ordinance.

Garcetti added that the rules will help encourage more people to get the shot and make businesses “safer for workers and customers.”

Operators of indoor locations or large outdoor events are asked to check for patrons’ vaccination statuses under the new rules and may be issued a citation for non-compliance. On first offense, the operator will receive a warning and notice to correct. The operator of the venue could then face a fine of $1,000 for a second violation, $2,000 for a third violation and $5,000 for a fourth and each subsequent violation.

While the mandate kicks in on Monday, enforcement — through inspectors from the city’s Department of Building and Safety — will begin starting on Nov. 29.

Los Angeles County data indicate that some 80.2% of residents ages 12 and older have received at least one does of a COVID-19 vaccine as of last week and 72% are fully vaccinated.

Los Angeles joins a growing number of municipalities mandating the coronavirus vaccine for indoor venues. A similar indoor vaccine requirement went into effect in New York City in August, though its rollout sparked backlash.

Despite a small yet vocal faction of Americans opposing the shot, health officials have reiterated that COVID-19 vaccines are safe and effective at reducing hospitalizations and deaths from the virus.