One in three residents of Los Angeles County have been infected with the Wuhan coronavirus, according to recent estimates by county scientists.

“The estimate, based on scientific modeling, means officials believe more than 3 million of L.A. County’s 10 million residents have been infected with the coronavirus, including nearly 13,000 who have died,” the Los Angeles Times reported Thursday.

The number is more than triple the cumulative number of cases that have been confirmed through testing and continues a trend that has been worrying authorities since late last month.

“Officials have long believed that testing only captures a certain percentage of those who are infected because many with the virus don’t show symptoms or suffer only mild symptoms,” the Times article said.

However, the rising number of infections has slowed the pace of coronavirus transmission “as the virus is increasingly coming into contact with people who have survived the infection and likely developed immunity,” the report continued:

“Unfortunately, we are still engaging in behaviors that facilitate spread of the virus, so it is still able to find plenty of susceptible people to infect,” said Dr. Roger Lewis, director of COVID-19 hospital demand modeling for the L.A. County Department of Health Services.

About 75% of L.A. County’s population will need to be immune to the virus through widespread vaccinations to dramatically slow its spread, Lewis estimated. Even if half of L.A. County’s population were immune, “and yet we decide to just pretend that we don’t have to take precautions, we will still have a very, very devastating pandemic.”

Last week, the county’s Emergency Medical Services Agency reportedly told ambulance teams to leave behind patients they are unable to resuscitate at the scene as hospitals move past capacity, Breitbart News reported:

Additionally, these first responders have reportedly been instructed to attempt resuscitation for at least 20 minutes at the scene but to leave any patient that does not regain respiration or pulse. While the odds of such a patient surviving are remote even in the best of times, ambulances would typically still attempt to bring the patient to the hospital.

On Tuesday, Los Angeles Mayor Eric Garcetti said the coronavirus vaccine is being “rolled out in phases, with our most at-risk populations being prioritized first”.

Over the past week, Los Angeles County averaged more than 15,000 additional coronavirus cases a day, “one of the highest such rates seen so far in the pandemic,” the Times article said.