WASHINGTON

New York City, the most populous city in the United States, will require all municipal employees to be vaccinated against COVID-19 or face weekly testing, Mayor Bill de Blasio announced on Monday.

The measures are being enacted for the city’s 300,000 municipal workers, including teachers, police officers and firefighters, amid fears over the spread of the highly infectious Delta variant.

The mayor pointed to the India-origin variant in announcing the new measures, saying it has “thrown us a curveball” as the US attempts to return to a semblance of pre-pandemic normalcy.

“This is about our recovery. This is about what we need to do to bring back New York City,” de Blasio said during a press conference.

The New York City vaccination mandate will go into effect Sept. 13, the first day of the city’s school year when many students are expected to return to in-person learning.

De Blasio is also mandating that beginning Aug. 2 all unvaccinated city government workers must wear masks at all times while they are working, or get vaccinated immediately.

“This is very, very clear. We will have to unfortunately be very tough. If a city government employee does not wear a mask indoors and they are unvaccinated there unfortunately will have to be consequences,” the mayor said. “If someone’s unvaccinated unfortunately they pose a threat to themselves, but they also have a greater chance of spreading the disease.”

New York City was the epicenter of the US outbreak early on in the pandemic as the city ground to a halt, and mass graves were dug for victims as hospitals buckled.

While daily cases are nowhere near the levels seen in the pandemic’s early days, there has been a marked increase in daily cases since early July.