The coronavirus killed another four medical professionals in Los Angeles County last week, all of them employees at skilled-nursing and assisted-living facilities, where the respiratory disease’s impact remains devastating.

The virus has claimed 15 health care workers’ lives in the county, and 80% of them worked in nursing or assisted-living homes, Dr. Barbara Ferrer, L.A County’s public health director, said in the department’s Monday news briefing.

“As a community, we mourn the passing of these health care workers who dedicated their lives to healing others,” she said. “And to their families and friends, our thoughts and prayers are with you.”

There are now 2,978 confirmed cases among health care workers and first responders in the county — a 51% increase from the previous week, while the number of infections overall increased by 28%, according to public health data.

But that doesn’t mean the virus is necessarily spreading faster among the medical community.

“This large increase is due in part because of the increased testing that we’ve been doing, particularly in our skilled nursing facilities,” Ferrer said.

The county announced on April 22 that it would begin testing all residents and staff at institutions like nursing homes, regardless of whether they have symptoms, in an attempt to address the outsized toll the virus is taking on the facilities. Once that effort began, officials said most people who tested positive weren’t exhibiting any symptoms.

Just under half of all 1,256 coronavirus-related deaths in L.A. County are tied to institutions where people live in close quarters, including jails, shelters and long-term care facilities — with nursing homes being hit the hardest.

Medical professionals were infected across two dozen different occupational settings in L.A. County, but the vast majority of those sickened work in hospitals and nursing homes.

Employees at nursing facilities account for 44% of all health care worker cases, while those at hospitals account for 30%, according to Ferrer.

Nurses still account for the majority of positive cases, but they’re also the “largest health care worker group,” Ferrer said. Caregivers, administrators, doctors and medical assistants have also been infected.

Not all medical professionals who tested positive knew their source of exposure. But for the 56% who did, 78% said they were infected at a health care facility.

Since the start of the outbreak, 7% of health care workers sickened have been hospitalized, Ferrer said.

“Your contribution to our community can not be understated,” she told the front-line workers. “You are all truly amazing.”

The medical professionals included in the data all work in L.A. County, although some may reside elsewhere. And they’re included in the tally regardless of where they caught the virus.

Deaths in L.A. County’s medical community account for nearly half the statewide total of 32, according to the latest figures available from the California Department of Public Health.

The county’s nearly 3,000 confirmed cases also account for almost half the 6,100 reported to the state. The same is true for cases and deaths among the general population as L.A. has emerged as the epicenter of the virus in the state.