(CNN) A federal judge has turned down a request to let more than 40 unvaccinated children return to classes in a suburban New York school, while there's a measles outbreak in the area.

Since December 7, the students from Green Meadow Waldorf School in suburban Rockland County just north of New York City, have had to stay home from school, in response to an exclusion order issued by the Rockland County Department of Public Health.

Green Meadow is a K-12 school with about 300 students enrolled.

Rockland County public health officials are reporting 146 total cases , with 82% of the patients not having had the MMR vaccine, for measles, mumps, and rubella. Measles is a highly contagious respiratory disease, which was largely eliminated in the US by the early 2000s.

An international traveler is believed to have introduced measles into the county last September, leaving the unvaccinated vulnerable to falling ill.

More than 20 parents are listed on the lawsuit, identified only by their initials.

Children have to stay home

Thomas Humbach, the county attorney, defended the exclusion order while speaking to media Tuesday.

"The Supreme Court has held that the public health is a primary objective of the government, and we have to stand strong for the protection of the babies and the infirm who would be affected by this disease," he said.

Humbach stressed that the case isn't over and the county will continue to hold its position that unvaccinated children in the county needed to stay home from school during the measles outbreak. "With any luck, the measles outbreak will end before the case does," Humbach said.

In a letter to school administrators in Rockland County, Dr. Howard Zucker, New York state's health commissioner, designated Rockland County Public Heatlh Commissioner, Patricia Ruppert, as having authority to order students excluded from classes if there "have been one or more recently confirmed cases of measles." Zucker noted that the exclusion order could last for a period of "21 days after the last exposure."

Zucker added that "Affected schools should also take appropriate steps to ensure that unvaccinated students are able to continue with coursework from home."

Ruppert imposed the school exclusion order for unvaccinated children on December 5. At the time, county officials said Green Meadow's vaccination rate was just 33%, but that number has since increased to about 56%, according to the Rockland/Westchester Journal News

Still that number is far short of the 95% figure many public health officials cite as necessary for a community to achieve immunity to various communicable diseases.

Parents are scrambling to take care of children

Michael Sussman, an attorney representing parents and students forced to stay home, also spoke to press following the judge's decision. He called the county's exclusion order "over broad," arguing there hasn't been a single measles case reported in the school or its broader community of Chestnut Ridge.

Rockland County says the measles cases are clustered in eastern Ramapo, a few miles away from Green Meadow Waldorf School. In a notice posted online by Rockland County, officials noted, "Due to Rockland County's small geographic size, exposure to the measles may occur anywhere in the county."

But Sussman said he didn't think the law allowed health officials to exclude children from a school without a reported case at the school.

One woman speaking on behalf of "49 children from one school" said her child had been out of school for 93 days.

Another parent said "the stress and the burden on the whole family has been enormous," making it harder for parents to earn a living and take care of children who couldn't be in school during the day. He said the county had overreached with its "unprecedented and ambiguously worded policy," causing parents to "miss work, hire tutors, and live on reduced income." He said some students had missed entire seasons of sports they played.

Sizable outbreak in Washington state

The CDC has counted 228 measles cases in 2019, a number well on its way to rivaling 2018's count of 372 US cases, which was the second highest in two decades.

This week, 22 of those cases were new.

The outbreaks in Brooklyn and New York City suburbs have centered on observant Jewish communities, and are connected to travelers who have been in Israel. In addition to New York, there is also a sizable measles outbreak in the state of Washington, with 75 affected.

Cases have also been reported in New Hampshire, California, Colorado, Connecticut, Georgia, Illinois, Kentucky, New Jersey, Oregon and Texas.