So, last week, Rainier Popup Kitchen moved to a grab-and-go model, filling more than 100 bags with sandwiches, fruit, water bottles, vitamin C packets, and pamphlets with tips on limiting the virus’s spread. Volunteers over 60 were instructed to stay home, and anyone feeling sick was also barred from helping with off-site food prep. Those deemed low-risk enough to hand out meals did so wearing gloves and respirator masks. To discourage lingering and minimize contaminated surfaces, they didn’t set up tables or chairs. This time, the regulars had little to do but pick up food and leave.

Read: The dos and don’ts of ‘social distancing’

Even during a period of widespread social upheaval, this sudden erosion of the sense of community the lunch fostered was perhaps the hardest adjustment to accept. “It was a really difficult decision to ask people not to come, and to have to have those kinds of barriers between us,” Serina Holmstrom, one of the organizers, told me. When a diner with whom she’s especially close came up to hug her, Holmstrom had no choice—for both their sakes—but to stop her and offer an elbow bump instead.

More than half a million people experience homelessness in America, according to a recent estimate published by the Department of Housing and Urban Development, although experts say many of the one-night surveys that inform these data are undercounts. About two-thirds of these people spend their nights in shelters; the remaining third of them are unsheltered, sleeping in cars, tents, or parks. The crisis is especially acute in large, dense urban areas, where economic inequality and high costs of living make lower-income people more susceptible to housing instability. Together, New York City and Los Angeles are home to nearly a quarter of all people experiencing homelessness in the United States, and more than half of the nation's unsheltered homeless population lives in California.

Read: Nobody knows what to do about L.A.’s homelessness crisis

For the most part, homeless services come courtesy of a large array of nonprofit organizations and volunteer groups, which fund their operations using some combination of in-kind donations, philanthropy, grants, and contracts with state and local governments. Even in ideal circumstances, meeting the basic needs of unhoused people is a daunting challenge, and providers rely on the free labor of volunteers to meet it as best they can.

Already, the coronavirus pandemic has laid bare the fragility of this patchwork social safety net. Experts say COVID-19, the disease caused by the coronavirus, is most dangerous to older and immunocompromised people, two groups to which those experiencing homelessness disproportionately belong. Last year, health clinics affiliated with the National Health Care for the Homeless Council served 1 million people, according to the senior director of policy Barbara DiPietro; 40 percent of them were 50 or older. Rates of tuberculosis among the homeless population are 10 times higher than the national average, and DiPietro estimates that on any given day, about a third of patients present with a fever, a cough, or other symptoms of respiratory illness.