The flood of migrant families into New York City is forcing schools to accept children who lack required vaccinations and has possibly led to one outbreak already.

The Simon Baruch Middle School in Gramercy Park had a chickenpox case, according to a Jan. 25 notice from the principal which said students not vaccinated for the illness could not attend school.

A parent at the school said after the announcement, five migrant children were absent for a few days from the class in question

“When you are talking now about hundreds of children entering a school and coming from countries where we know the same childhood vaccinations are not available— it’s hard to not see where vulnerable families could be put at risk,” the parent said.

A top city health official recently told the City Council that a surprising number of migrant children who had never had a single shot were arriving in the Big Apple.

“We’re seeing so many unvaccinated kids,” Dr. Ted Long, executive director of the NYC Test & Trace Corps, said at a council hearing, speaking generally about the migrant influx.

An estimated 11,000 migrant children have enrolled in Department of Education schools since the summer.

The city Health Department tracks outbreaks of illnesses like chickenpox but refused to say how many it has recorded in city schools since September or comment on the Simon Baruch situation.

Carolina Chicaisa, who arrived in New York from Ecuador on Jan. 8, said her 8-year-old-son, Jareth, has been attending third grade at PS 111 in Hell’s Kitchen since last week without a record of his vaccinations.

“I had proof of them from Ecuador, but I lost them in the jungle on our way here,” Chicaisa said.

She said she took Jareth for blood tests to prove he was vaccinated and was waiting for the results to show to the school, which has been overwhelmed with migrant students. He is allowed to attend class until they get the proof.

Another mom from Ecuador said her son has been attending eighth-grade classes at the City Knoll Middle School, which is located in the same West 53rd Street building as PS 111, for about two months although his shots were not up initially to date.

“A month ago they asked for the vaccine records, and he did have vaccines in Ecuador but he still had to go have six more. I don’t even remember which ones he got,” said the mom who declined to give her name.

Students in kindergarten through fifth grade are required to get the chickenpox vaccine as well as the DTaP, MMR, polio, and hepatitis B shots. At least two doses are required for each of the vaccines.

Students are not required to be vaccinated against COVID-19.

DOE rules say schools must accept kids living in temporary housing, including asylum seekers, even if they can’t immediately show vaccination or academic records, according to guidance sent to principals in September.

“Students transferring from another state or country, including asylum seekers, have 30 days from their enrollment to provide evidence of vaccinations or be in the process of acquiring vaccinations,” the guidance says.

They are allowed to attend school during this 30-day period.

Students who are not migrants or in temporary housing need at least the first dose in a vaccine series to provisionally remain in school. They then need to provide proof that follow-up shots have been scheduled or risk getting excluded from school, according to DOE rules.

“Both DOE and DOH work closely with families to ensure they have access to immunizations services and are in compliance with the school requirements to prevent outbreaks,” DOH spokesman Patrick Gallahue said.

Test & Trace Corps staff have given in excess of 4,600 shots to more than 1,800 kids, a spokesman told The Post.

The Simon Baruch principal did not immediately return a request for comment nor did a DOE spokesman.