“The Delta variant has thrown us a curve ball,” Mayor Bill de Blasio said in a briefing on Monday. “If someone is unvaccinated unfortunately they pose a greater risk.”

The city’s broad vaccine mandate expands a policy announced last week that requires health care workers in public hospitals and clinics to be vaccinated by Aug. 2 or submit to weekly tests. Foster care, senior center or shelter staff will be required to be vaccinated by Aug. 16, with the mandate applying to the whole city workforce by the first day of public school in mid-September.

“This means everybody,” he says, noting schoolteachers, police, fire officials, front line and office workers.

About 60% of the city’s more than 42,000 public hospital employees have been vaccinated, according to Mitchell Katz, president and chief executive officer of the system. Only 54% of people are fully vaccinated in the city, which missed its goal of fully vaccinating 5 million New Yorkers by the end of June. Just over 4.5 million New Yorkers are fully vaccinated.

“Don’t wait: The virus is here now and it’s transmitting quickly due to the Delta variant, a particularly aggressive strain of the virus, with cases rising rapidly particularly among unvaccinated,” said Health Commissioner Dave Chokshi.

De Blasio also urged private employers to start requiring the shots and said the rise in cases was largely among unvaccinated residents. The city recorded 1,074 new cases of the virus July 22, compared with 56 daily cases June 21, although hospitalizations have remained low, with only 28 reported July 22.

“My message to the private sector is go as far as you can go right now,” he said. “I would strongly urge a vaccination mandate.”