Less than 1% of NYC's municipal workers face termination Friday over vaccine status

About 4,000 New York City municipal workers are facing termination Friday for not being vaccinated against COVID-19.

Less than 1% of the city's workforce will lose their jobs if they don't show proof of vaccination -- potentially the country's largest workforce reduction linked to COVID vaccines.

The 4,000 employees include 3,000 workers who are on unpaid leave and 1,000 new workers who were hired after Aug. 2, 2021, who were told they had to be vaccinated as a condition of employment.

"I want them to stay, I want them to be employees of the city, but they have to follow the rules that were made before my administration," Mayor Eric Adams said during a press conference Thursday. "We have to be very clear. People have to be vaccinated if they are a New York City employee. Everyone understood that and we have to follow that."

The mandate was first announced in October 2021 by then-New York City Mayor Bill de Blasio for roughly 370,000 city employees -- including police officers, firefighters, corrections officers and teachers -- to either be vaccinated by the end of month or be placed on unpaid leave.

When the mandate was first announced, about 84% had received at least one dose, according to City Hall, which rose to 95% by January. Several exemptions have also been granted.

The unpaid workers must submit proof of their first dose by day's end and then have 45 days to receive a second dose. The new workers, on the other hand, submitted proof of an initial dose when they were hired and now must show they've completed their vaccine series.

Adams said some workers who were facing termination have since submitted their proof of vaccination so it's not clear how many employees will be fired.

During the press conference, Adams stressed that any workers who have not yet been vaccinated weren't being fired, but are rather "quitting" on the city.

"We are not firing them. People are quitting," he said. "The responsibility is clear. We said it, 'If you were hired, if you get this job, you have to be vaccinated. If you are not following the rules, you are making that decision. You are making the decision that you are not going to follow the rules of getting vaccinated and that is a decision they are making.'"

Hundreds of workers protested the mandate earlier this week, marching across the Brooklyn Bridge.

Additionally, a religious rights group filed a lawsuit in Brooklyn Federal Court Thursday on behalf of unvaccinated city workers, claiming the mandate violates their religious and constitutional rights.

The plaintiffs, which include firefighters, a corrections officer, a sanitation worker, a social worker and a police officer, say the mandate is "openly discriminatory" against "people with personally held religious beliefs or unorthodox religious beliefs."

ABC News' Mark Crudele contributed to this report.