Health insurance coverage was cut off Sunday for thousands of Montefiore nurses as the largest nurses strike in New York City entered its fourth week.

As the strike continues, workers are paying more than $1,000 a month for health insurance — even more for families.

“Trying to apply for COBRA and so expensive. Or to get a marketplace plan,” said Anne Farrington, a Montefiore nurse of 15 years.

Farrington has spent nearly every day on the picket line. She said she is fortunate to have secondary insurance through her spouse, but many coworkers are not as lucky and are struggling without a paycheck.

Picketers braved the cold Sunday at the Montefiore Einstein campus in Morris Park. More than a week ago, Montefiore warned nurses that if they did not return to work by Feb. 1, they would forfeit their health insurance coverage. Sunday marked that deadline, and nurses on the line said they have no intention of returning until their demands are met.

The strike began 21 days ago after the New York State Nurses Association called on hospitals to address safe staffing levels, improve health benefits and take steps to prevent workplace violence. After weeks of negotiations, the union says no agreement has been reached.

As some hospitals increase pay for travel nurses to up to $28,000 a month to address staffing shortages during the strike, union nurses say they remain firm in their demand for contract improvements.

“We need safe staffing,” Farrington said. “In the emergency room, patients are packed together. It’s not dignified. We need better care for our patients.”

In a statement, the New York State Nurses Association said, “We streamlined and revised our proposals in an effort to bring hospital executives back to the table to negotiate in good faith and settle fair contracts... Now hospitals need to get serious at the bargaining table, end this strike.”

Nurses are expected to return to the bargaining table on Monday.