The Rockland County Executive says the ban on unvaccinated minors is effective

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A dose of measles vaccine is being tested at the Miami Children's Hospital on June 2, 2014 in Miami, Florida.

In response, government officials declared the state of emergency Tuesday and banned unvaccinated children in public places, including shopping centers, schools and restaurants, for 30 days.

"We think we are on track to get a vaccination rate of at least 93% with the first vaccine," Day said.

The current rate for under-18s is 72%, he noted. Health officials said the best way to curb the spread of the disease was a 92 to 95 percent vaccination rate in the community.

The measles vaccine, called MMR, also protects against mumps and rubella and is given in two doses. The CDC recommends that the first be administered between 12 and 15 months and the second between 4 and 6 years. The combination is 97% effective in preventing the disease, while a dose is effective at around 93%, says the CDC website.

What is happening in Rockland County is part of a growing trend towards the fight against vaccination. Parents, especially in the richest and most educated areas of the country, refuse to vaccinate their children. The highest refusal rate is recorded in the Nbadau-Suffolk area of ​​New York, which includes most of Long Island. 14.2% of parents refused to give their children at least one vaccine, according to a January 2018 report from Blue Cross Blue Shield.

"There are far too many things happening around me – it's a better situation," Day said. "The immunity of the flock is of utmost importance."

– Angelica LaVito, CNBC, Joe Tempesta and AP contributed to this report.