WASHINGTON — Officials across the U.S. are preparing for a potential coronavirus outbreak among the homeless, particularly on the West Coast, where there is already a concentration of cases and the large homeless population has experienced past outbreaks of diseases like typhus.

The homeless are among those at highest risk because they sleep together in close quarters in shelters, are less likely to see doctors and have a higher prevalence of respiratory problems and other chronic health issues that make them more vulnerable, according to public health officials and advocates for the homeless.

"All these preventive things that are being done, like washing your hands — they can't do any of those. They don't have access to that," said Nan Roman, president and CEO of the National Alliance to End Homelessness, an advocacy group. "We need to make sure that homeless people get the services they need so it doesn't spread to everyone else."

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No outbreaks have been reported in homeless shelters or encampments to date. But state and local authorities say they are stepping up their preparations, having worked to combat outbreaks of tuberculosis, hepatitis A and typhus among the homeless in recent years.

Of particular concern is the growing number of homeless people on the West Coast, where there has been a high number of confirmed cases of coronavirus. Homelessness in California increased by 16 percent last year, according to the Department of Housing and Urban Development. There are an estimated 568,000 homeless nationwide.

In Los Angeles, members of the City Council are calling for local authorities to install hand-washing stations at homeless encampments, and the city Health Department is meeting with representatives of all homeless shelters to determine how to isolate sick patients.

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In Seattle, King County officials say no homeless people have required testing so far, but they plan to set up modular housing for homeless people who become infected, and they are buying a local motel for those who cannot quarantine themselves at home. City workers also have been handing out sanitation kits to the homeless, according to the Seattle mayor's office.

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In Maine, state officials are conferring with shelters and community health centers to determine where homeless patients could be quarantined, said Dr. Nirav Shah, director of the Maine Center for Disease Control, who added that decommissioned college dormitories may be an option.

Some states have considered renting hotel rooms to quarantine those without fixed addresses, but the idea quickly met resistance from the hotel industry, said Dr. Marcus Plescia, chief medical officer at the Association of State and Territorial Health Officials, which represents public health agencies.

"A lot of hotels were concerned about the public impact of being the 'coronahotel,' and who's going to want to stay there in the future?" said Plescia, adding that some states are planning to use temporary housing like RVs, instead.

More federal support could be coming soon. On Thursday, the Senate passed an $8.3 billion emergency bill to combat coronavirus, which includes funding for "the construction, alteration, or renovation" of facilities. State and local authorities could use the money to house those who cannot self-quarantine at home, said Adriane Casalotti, chief of government and public affairs for the National Association of County and City Health Officials, which represents local health departments. The bill, which passed the House on Wednesday, is headed to the president's desk.

Next week, the federal government's U.S. Interagency Council on Homelessness will host a webinar with the Centers for Disease Control and Prevention and homeless experts from King County, Washington, to help homeless shelters and other providers prepare.

"King County is a little bit ahead of everyone, for good reason, and we are trying to share what they have done," said Katy Miller, a Seattle-based regional coordinator for the homelessness council. The agency has distributed a sanitation and hygiene checklist for homeless shelters in King County, the San Francisco Bay Area and other affected areas with high homeless populations.

Homeless shelters are devising their own protocols for those who display symptoms of coronavirus or have been exposed to diagnosed patients.

"We immediately give them a mask and move them into an isolated office. We then assist the individual as they contact a triage nurse line," said Terry Pallas, chief program officer for Union Gospel Mission, a homeless shelter in Seattle. "If the medical provider recommends that the individual be seen, we will then help the individual get to the hospital or clinic."

The Seattle shelter has set up a separate space for patients released from hospitals or clinics who are homeless.

An outbreak among the homeless could also expose shelter workers and police who work closely with the population.

Last week, a Los Angeles police officer sued the city after he became severely ill from contracting typhus on the job last year and then infected his wife, alleging that the city failed to take adequate precautions to protect the health of its officers, especially in areas of high homelessness.

The city attorney's office, which represents the police department, declined to comment on pending litigation.