This story was updated at 5:30 p.m.

Long-term care facilities in Maryland are the sites of thousands of confirmed cases of coronavirus, according to data published Tuesday evening by the state’s health department. Maryland Governor Larry Hogan also signed an Executive Order Wednesday, requiring universal testing of all nursing home residents and staff in the state.

As of Wednesday afternoon, there are 4,822 cases of COVID-19 in such facilities and group homes of more than 10 people in Maryland. More than 500 residents and staff associated with those facilities have died of the virus. Maryland’s data includes information from elder care facilities, group homes and correctional facilities, and will be updated weekly.

Residents of long-term care centers are especially vulnerable to the coronavirus. They live in close quarters with communal spaces, and in some cases, need daily in-person care from staff — who sometimes work at multiple such facilities. Many residents have existing health conditions that can make their cases of COVID-19 especially severe.

Montgomery County’s congregate settings have been hit the hardest in the D.C. region, with 1,099 cases and 149 deaths across about 50 facilities. The populous county also makes up the highest infections and deaths at facilities in the state. Prince George’s County has 519 cases and 40 deaths, and Anne Arundel County has 387 cases and 52 deaths.

Facilities in the Baltimore region are also struggling with the virus. Baltimore County has 837 cases and 71 deaths, followed by Baltimore City, with 662 cases and 41 deaths.

Sagepoint Nursing and Rehabilitation in La Plata, Maryland, has the highest death toll in the state, with 35 dead and 129 confirmed cases. That surpasses Pleasant View Nursing Home in Mount Airy, one of the earliest-publicized outbreaks in the state. Twenty-eight people there have died, with 124 testing positive.

Some advocates note that those case numbers provide an incomplete picture, in the absence of universal testing of all residents and staff in facilities.

“We know that so many individuals that have this virus are asymptomatic and so it’s really the only way to effectively identify who has the virus and who doesn’t,” Allison Ciborowski, a spokesperon with LeadingAge Maryland, said.

Furthermore, some facilities in the state have set aside parts of their buildings to accept individuals with COVID-19 who were recently discharged from the hospital — cases that are also represented in counts of people with the disease.

“The data does not really tell the full story,” Ciborowski says.

The Department of Health moved to release the information after Governor Larry Hogan ordered it to be made public on Monday.

But the release of the nursing home data represents a significant switch for the state. Last week, the Maryland Department of Health instructed local public health departments to not publicize the numbers of nursing homes or names of specific facilities, citing health privacy concerns.

“The state gave us all guidance earlier this week that while we can talk about the number of cases, we can’t say we have X number of facilities with cases,” a spokeswoman for the Montgomery County Department of Health told WAMU last week. She also declined to give updates on specific facilities, again citing state guidance.

D.C. has also made information about long-term care facilities with cases of the virus public. In an update last week, the city reported that 14 nursing homes had residents or staff who had tested positive, and a combined total of almost 200 cases and 14 deaths. One facility, Transitions Healthcare Capitol City, accounts for more than a quarter of those cases, with 53 residents and 3 staff members sick.

Virginia is not publicizing long-term care coronavirus information, citing privacy concerns.

“The current VDH policy is if a facility consents to have its name released to the public, then we will confirm that,” Tammie Smith, a spokeswoman for the Virginia Department of Health wrote in an email. “However if the facility does not want to be named, we cannot release that information.”

“VDH is not able to release disease information at the facility level to the media because that would compromise the anonymity of the patient,” she said.

Nursing homes in the state can share information with one another, however.

Long-term care facilities in Virginia make up 116 of the state’s 206 coronavirus outbreaks, accounting for 1,407 cases and 111 deaths.

On April 19, Centers for Medicare and Medicaid Director Seema Verma directed nursing homes to report coronavirus outbreaks to the Centers for Disease Control and Prevention, as well as local health departments.

The Centers for Medicare and Medicaid is also developing a new rule that would require facilities to notify residents and their families about new cases of COVID-19 in the facility. That rule would require notification within 12 hours of a single confirmed positive case of the virus, or when three or more residents or staff have an onset of respiratory symptoms within a 72-hour period. After that, facilities will be required to update residents and their families weekly, or every time a new positive case or cluster of respiratory infections occurs.

Dominique Maria Bonessi contributed reporting. 

This story was updated to update case and death numbers, clarify that case and death numbers for long-term care facilities in Maryland include both residents and staff, and add comment from Allison Ciborowski, a spokeswoman for LeadingAge Maryland.