“We’re simply describing the patients who came in and required hospitalization,” she said. “We are not comparing them to those who were positive and stayed out of the hospital, or who didn’t get infected, or to patients with any other disease.”

The researchers reported that when patients first came to the hospital and were triaged, 17 percent had an abnormal respiratory rate of more than 24 breaths per minute, and 28 percent received supplemental oxygen.

But fewer than one third of the patients had a fever, even though they were sick enough to be hospitalized, a similar observation to one noted by a large Chinese study. That has important policy implications, indicating that taking people’s temperatures in order to screen them for the coronavirus — a measure that was used on cruise ships and as a way to detect illness in returning travelers at airports, and that has also been proposed for use in the workplace — is likely to miss many people who are not only asymptomatic but also acutely ill.

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Nearly 60 percent of those hospitalized at the Northwell facilities had high blood pressure, 40 percent were obese, and about one-third had diabetes. Smaller numbers of patients suffered from other chronic illnesses, such as heart disease, kidney disease and chronic respiratory illnesses.

Other smaller reports from New York City area hospitals have also highlighted obesity as a complicating risk factor. One hypothesis is that obesity causes chronic, low-grade inflammation that can lead to an increase in circulating, pro-inflammatory cytokines, which may play a role in the worst Covid-19 outcomes.

Dr. Leora Horwitz, an associate professor at NYU Langone Health whose recent study of Covid-19 patients found that obesity was the most significant predictor of disease severity after age, said that the new paper described similar rates of chronic disease and obesity, but that it was descriptive, so “it is hard to tell the relative importance of the various comorbidities.” She noted that the obesity rate on Long Island is 24 percent, suggesting the hospitalized patients “are disproportionately obese.”

The report adds new evidence of the greater susceptibility of men to the coronavirus: Men represented 60 percent of the hospitalized patients in the Northwell system, and an even greater share — 66 percent — of the patients treated in the intensive care unit.