A report released Wednesday by the Centers for Disease Control and Prevention (CDC) revealed that 66% of homeless people in a San Francisco shelter tested positive for coronavirus, renewing concerns about indoor housing during the pandemic.

The Morbidity and Mortality Weekly Report (MMWR) investigated 19 homeless shelters nationwide, including 15 in Seattle, one in Boston, two in Atlanta, and one each in Boston and San Francisco. Overall, the average prevalence of coronavirus among residents was 25%, and the average prevalence among staff was 11% (and 16% in San Francisco). San Francisco’s result was particularly striking — not only because it was so large, but because the overall infection rate in the area was low.

The report explained (footnotes omitted):

Homelessness poses multiple challenges that can exacerbate and amplify the spread of COVID-19. Homeless shelters are often crowded, making social distancing difficult. Many persons experiencing homelessness are older or have underlying medical conditions, placing them at higher risk for severe COVID-19–associated illness. To protect homeless shelter residents and staff members, CDC recommends that homeless service providers implement recommended infection control practices, apply social distancing measures including ensuring residents’ heads are at least 6 feet (2 meters) apart while sleeping, and promote use of cloth face coverings among all residents.

San Francisco is attempting to move homeless people into individual hotel and motel rooms to minimize the spread. It is also allowing homeless people who currently live in tents on the street to remain there, because of the higher risks of spreading the coronavirus indoors in congregate settings. A recent CDC paper suggested outdoors spread was far less likely.

Los Angeles has faced criticism for its policy of moving homeless people into temporary shelters set up in recreation centers in residential neighborhoods, contrary to CDC guidelines: “Unless individual housing units are available, do not clear encampments during community spread of COVID-19. Clearing encampments can cause people to disperse throughout the community and break connections with service providers. This increases the potential for infectious disease spread.”

The CDC recommends providing services to people outside, and encouraging “social distance,” until individual housing units can be found.

Los Angeles is currently using mobile trailers to provide individual housing for homeless people who test positive for coronavirus, as witnessed by Breitbart News at a recreation center in Westwood last week.

Mayor Garcetti said Sunday in his “State of the City” address that authorities are trying to find hotel and motel rooms: “we have a new county-wide plan to find thousands of hotel and motel rooms to prevent the spread of the virus among people experiencing homelessness. And once those fellow Angelenos come inside, they must not return to the streets.”

Joel B. Pollak is Senior Editor-at-Large at Breitbart News and the host of Breitbart News Sunday on Sirius XM Patriot on Sunday evenings from 7 p.m. to 10 p.m. ET (4 p.m. to 7 p.m. PT). His new book, RED NOVEMBER, is available for pre-order. He is a winner of the 2018 Robert Novak Journalism Alumni Fellowship. Follow him on Twitter at @joelpollak.