There are now 20 confirmed cases of the coronavirus in the city — including a 7-year-old girl from the Bronx and a city government worker, Mayor Bill de Blasio said Monday.

Hizzoner said the little girl attends the Westchester Torah Academy in White Plains, Westchester County, and is quarantined at home and doing “well.’’

She has no pre-existing conditions or a recent travel history and is showing “minimal symptoms,” de Blasio said.

The child’s mother, father and two sisters have all tested negative, he said.

A city employee also has tested positive for the potentially deadly bug, de Blasio said.

The worker, who lives in Westchester County, “was in a city office last week but only for three hours,’’ the mayor said.

The man was not symptomatic at the time and still isn’t, he said.

The patient is in quarantine, de Blasio said, adding that all of his family members tested negative for the virus.

But the mayor said a stricken 65-year-old man from Queens with diabetes is “critically ill’’ and “someone we’re very, very worried about.’’

He said the man had a fever, then developed pneumonia and shortness of breath and ended up in the ICU.

The other new coronavirus patients in the city include a 68-year-old man in Brooklyn who recently traveled, although not to any of the hot-spot countries, so it’s unclear where he contracted the virus, de Blasio said.

The man, who has diabetes and heart disease, had symptoms and was admitted to the ICU at a private hospital in Brooklyn. He is currently critical but stable, the mayor said.

A 22-year-old man in Brooklyn also had symptoms and was transported by EMS to a private hospital in the borough.

“Why is a 22-year-old man stable but hospitalized at this point?’’ de Blasio told reporters. “The one factor we know of is he is a vaper.

“We think the fact that he is a vaper is affecting this situation.’’

Hizzoner said there is at least one more case in the Bronx and related to the Westchester County cluster. Two more are in Manhattan — including Port Authority executive director Rick Cotton, he said.

“We’re seeing more and more cases related to community spread,’’ de Blasio said.