(The Center Square) – The president of the largest union of health care workers in the U.S. says it will fight companies requiring its members to have mandatory COVID-19 shots as a condition of employment.

The announcement came one day after Houston Methodist announced that 153 employees had been fired or resigned for refusing to get the shots as a condition of employment. Those suing argue requiring employees to receive a vaccine approved only through Emergency Use Authorization violates federal law. After a recent court dismissal, their attorney vowed to take the case all the way to the Supreme Court.

George Gresham, president of 1199SEIU United Healthcare Workers East, is weighing the organization’s legal options.

The New York-based union describes itself as the largest health care union in the U.S. and represents hundreds of thousands of nurses and caregivers in New Jersey, Florida, Washington, Maryland and Massachusetts.

“Whether there is a legal challenge that we can make, or whether it’s just a pure organizational challenge that we can make, we are not going to just give in,” Gresham said.

While Houston Methodist was the first to mandate the COVID-19 vaccine as a condition of employment, New York–Presbyterian Hospital was not far behind, implementing similar conditions but instead of a June deadline to comply, its given its employees a September 1 deadline.

“We care for sick people – some critically so – every day, and we are responsible for their safety while in our care,” the hospitals’ mandate states. “The stakes in this matter are high, and the evidence is clear that getting vaccinated against COVID-19 is the most important and responsible action we can take as NYP team members for the safety and well-being of our patients and visitors, our communities, and ourselves.”

Although Gresham says he’s received both doses and has encouraged union members to do so as well, he argues that workers “have the right to make their decision about their own health.” He met with New York-Presbyterian Chief Executive Steve Corwin to discuss union members’ concerns.

Union members are overwhelmingly against mandatory vaccination, he adds, even if they chose to receive the shots themselves.

Other hospitals in the New York City area are considering similar policies, the Gothamist reports.

But the New York State Nurses Association agrees with the 1199 SEIU. In a published statement it says, “NYSNA strongly opposes the mandatory vaccination of health care providers for COVID-19 as a condition of employment or as a state or federal mandate.”

As of June 22, Houston Methodist announced that 153 of its employees were fired or had quit during the previous two-week period.

“Many of my clients actually contracted COVID as a result of treating COVID-positive patients, and the thank you that Methodist Hospital gives them now is a pink slip,” their Houston-based attorney, Jared Woodfill, said.