N.Y.C. places dozens of school employees on unpaid leave, saying they used fake vaccine cards.

The New York City Department of Education this week notified dozens of school employees that they would be placed on unpaid leave effective Monday, after it said law enforcement alerted the department that they had provided false proof of coronavirus vaccination.

Law enforcement and the Special Commissioner of Investigation for the New York City School District are investigating the matter, according to Nathaniel Styer, a spokesman for the Education Department.

“Fraudulent vaccination cards are not only illegal, they also undermine the best line of protection our schools have against Covid-19: universal adult vaccination,” said Mr. Styer. “We immediately moved to put those employees — fewer than 100 — on leave without pay.”

The department would not reveal what evidence it had relied on to determine that the cards were fake. “If they have proof that they are vaccinated, they can show it,” Mr. Styer said.

Several of the employees told the city that they had followed the correct procedures and had received the notices in error, but they have yet to receive a response, according to the United Federation of Teachers, the teachers’ union. Mr. Styer said the department did in fact respond to the employees.

“It is wholly improper for the D.O.E. to unilaterally remove U.F.T. members from the payroll based on mere conjecture that vaccination documentation is fraudulent,” Beth A. Norton, a lawyer for the union, wrote in a letter to the department.

The teachers’ union demanded that the Education Department rescind the notices and ensure that the employees who received them remain on the payroll. The department declined to comment on the letter.

New coronavirus cases in New York City have increased 55 percent in the past two weeks, largely fueled by the highly contagious Omicron subvariant known as BA.2, according to The New York Times’s tracker. Hospitalizations have risen 10 percent over the same time period.

Mayor Eric Adams in March rolled back a number of pandemic restrictions, including a school mask mandate for students and educators that had been in place since the fall of 2020. Masks are still required at preschools and day care centers for children under 5, who are not yet eligible for vaccination.

Vaccine mandates are one tool officials have used to curb the virus’s spread in the city. Former Mayor Bill de Blasio in August announced a vaccine mandate for all educators, in an effort to reassure families and employees that schools would be safe when they reopened.

It was the first full vaccination mandate for city workers, and it applied to nearly 150,000 employees. Those who were not vaccinated by Sept. 27 were barred from entering schools and placed on unpaid leave, with health insurance, for a year.

The mandate compelled thousands of full-time school employees to get vaccinated, bringing the percentage who had received at least one dose of a vaccine up to 95 percent. About 8,000 workers refused at the time and were placed on unpaid leave.

All of the city’s active education employees are now fully vaccinated, Mr. Styer said.

A small group of teachers has repeatedly and unsuccessfully fought to overturn the mandate. In February, the U.S. Supreme Court rejected a request to block it.

A number of other city employees have been suspended based on what they provided to the city as proof of vaccination.

Dozens of the city’s sanitation workers were suspended without pay in November as part of an investigation into the use of fake vaccine cards. Two high-ranking police officers in December were also accused of submitting fake vaccination cards and were placed on modified duty.