The number of measles cases this year has climbed to 555 as of April 11, according to the Centers for Disease Control and Prevention.
"People are deciding not to vaccinate themselves or their children. And they're doing it based on false information," said Daniel Stapleton, Niagara County's Public Health Director.
The viral infection was eliminated in the U.S. in 2000. In 2014, there were 667 reported cases of measles.
"The incidents of measles across the world is up by 300% since the beginning of the year," said Stapleton.
In 1989, the CDC changed its recommendations for measles vaccinations from one to two doses.
One dose of the vaccine is 93% effective, while two doses of the vaccine are 97% effective.
At the time, the CDC urged people born between 1957 and 1989 to get two doses of the vaccine.
But now, Stapleton said that decision is up to your doctor.
"Your doctor will give out the recommended dosage, and will determine when you should have it. But those are very high efficiency rates," he said. "I mean that's something that, you don't get anywhere near that with the flu vaccine."
The Measles vaccine provides lifelong protection.
Stapleton said misinformation is putting lives at risk just as much as not vaccinating is.
"The risk from autism has been debunked multiple times. The physician who had that initial research lost his license to practice medicine."
Stapleton adds that 85% of those affected by the outbreak, including the one in Rockland County, are kids.
"We're talking children and people dying. Not just getting sick, they're dying," he said.
Stapleton said people who are at risk, and should get a vaccine, are those who aren't vaccinated, the elderly and those with compromised immune systems.
Those who live in or are going to an area with an outbreak should also check their vaccination records.