The number of measles cases reported so far this year is the highest tally in 27 years, U.S. health officials said Thursday.

The Centers for Disease Control and Prevention reported 971 measles cases for 2019. The new numbers pushed the national total above the 963 illnesses reported for all of 1994. The nation last saw this many cases in 1992, when more than 2,200 were reported overall.

"Measles is preventable, and the way to end this outbreak is to ensure that all children and adults who can get vaccinated, do get vaccinated," CDC Director Robert Redfield, M.D., said in a statement to Fox News.

"Again, I want to reassure parents that vaccines are safe, they do not cause autism. The greater danger is the disease that vaccination prevents."

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Measles, once common in the U.S., became rare after vaccination campaigns that started in the 1960s. A decade ago, there were fewer than 100 cases a year.

Overall vaccination rates have remained fairly high, but outbreaks have been happening in communities where parents have refused recommended shots, U.S. health officials say. Often, those parents express fears that the vaccinations themselves raise other health risks, like autism.

The latest spate of illnesses is scattered across 26 states, but most are in New York City.

The city's surge, which began last October, is already the largest local measles outbreak in the U.S. in nearly 30 years. It started when some unvaccinated children visited Israel, where a measles outbreak was occurring.

More than 500 cases have been diagnosed in two Brooklyn neighborhoods — Williamsburg and Borough Park — and they are mainly among unvaccinated children in Orthodox Jewish communities. Forty-two people have been hospitalized, including 12 treated in intensive care units.

More than 25,000 doses of vaccine have been given to children and teenagers in those two neighborhoods since October.

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Some have been motivated by a city order issued in April that all children and adults who live in four Brooklyn ZIP codes be vaccinated or face fines of up to $1,000. City officials say 123 people have received summonses for not complying with the order.

The city health department has put 400 people to work on the outbreak, and forged new relationships with community organizations to make a better case for vaccinations.

The officials believe it’s all paying off. New measles diagnoses dropped to 60 this month from 163 the month before.

The Associated Press contributed to this report.