Los Angeles County public health officials will require Universal Studios Hollywood and Six Flags Magic Mountain visitors and employees to provide proof of full COVID-19 vaccination or a recent negative test starting next month.

An amended county health order will require proof of COVID-19 vaccination or a recent negative test starting Oct. 7 for theme parks and other outdoor mega events of more than 10,000 people, according to Los Angeles County Public Health Director Barbara Ferrer.

“The health and safety of our guests and team members is our top priority as we comply with all L.A. County Health guidelines, which currently requires face coverings worn within all indoor venues regardless of vaccination status,” according to Universal Studios Hollywood officials.

Six Flags Magic Mountain officials said they are still awaiting further guidance on the new county health order.

The move by the county comes just as Universal and Magic Mountain are beginning to host thousands of visitors during annual Halloween events featuring haunted mazes, scare zones and live shows.

Mega event attendees who face “tons of exposure” to COVID-19 can later spread the virus throughout their families, coworkers and the community, Ferrer told county officials.

“This is a reasonable path forward that will position us to be better able to break the cycle of surges,” Ferrer told the Los Angeles County Board of Supervisors on Wednesday, Sept. 15.

California Gov. Gavin Newsom supports L.A. County’s move, but does not plan to extend the proof of vaccination order to the entire state, according to the Associated Press.

Federal, state and county officials across the United States have been reinstituting COVID-19 health and safety requirements throughout the summer to battle the spread of the Delta variant. Indoor and outdoor mega events are considered higher risk for COVID-19 transmission.

State officials lifted theme park mask mandates and most other coronavirus health and safety restrictions on June 15. Universal and Six Flags have required visitors to wear masks indoors regardless of vaccination status since mid-July under an L.A. County Public Health mandate.