As researchers begin to test homeless individuals in the United States for the virus that causes COVID-19, they’re discovering that the situation is out of control. Tests are rare. And outbreaks are spreading below the radar. For example, researchers found that only one individual out of 147 people who tested positive in a homeless shelter in Boston, Massachusetts, would have met the official criterion for testing — a fever1
. Missed cases are a major problem because the disease has been shown to spread like wildfire in shared living spaces such as nursing homes, prisons and shelters. The World Health Organization has said that, to open up their economies safely, countries must prevent the coronavirus from ripping through settings where people live together in close quarters. Singapore, for example, seemed to have successfully controlled the epidemic, until thousands of cases were discovered among migrant workers living in over-crowded dormitories. In the United States, a lack of action to protect homeless people — a growing population, as unemployment soars and prisons release people to ease overcrowding — threatens the nation’s response to COVID-19.