A new study of thousands of hospitalized coronavirus patients in the New York City area, the epicenter of the outbreak in the United States, has found that nearly all of them had at least one major chronic health condition, and most — 88 percent — had at least two.

Though earlier research has shown chronic conditions like obesity, high blood pressure and diabetes are common risk factors for severe Covid-19, the ubiquity of serious medical conditions in these patients was striking: Only 6 percent of them had no underlying health conditions.

“The number of patients who had chronic comorbidities surprised us,” said Karina Davidson, a senior vice president at the Feinstein Institutes for Medical Research, who was the paper’s senior author.