Possible explanations for the disparity have ranged from differences in behavior — smoking rates among men exceed those among women in much of the world, for example — to biological differences.

Women have more robust immune systems, some scientists have noted, that provide an edge in fighting off infections — although it also makes them more susceptible to autoimmune disorders.

Physicians working at hospitals throughout the city say the gender disparity is stark and impossible to miss.

“I’m in the emergency room, and it’s remarkable — I’d estimate that 80 percent of the patients being brought in are men,” said Dr. Hani Sbitany, a reconstructive surgeon at Mount Sinai Health Systems who has been treating Covid-19 patients in Brooklyn. “It’s four out of five patients.”