What to know about measles and Long Island

After being declared "eliminated" in the United States in 2000, confirmed cases of measles — a highly infectious disease — have hit a 33-year high at 1,288 so far this year. The U.S. Centers for Disease Control and Prevention said Wednesday that cases surpassed 2019, the year with the last big outbreak, when the country almost lost its status of having eliminated the disease.

While most of the cases have been centered around an outbreak in Texas, there have also been a handful in New York and on Long Island. Newsday asked infectious disease experts to explain what this means and what can be done to prevent a local outbreak.

Why have cases gone up so quickly in recent years?

There are outbreaks in unvaccinated or undervaccinated communities, as well as some cases from outside the United States, experts said.

The current outbreak includes more than 750 cases in Texas among several communities that were unvaccinated or undervaccinated, said Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Children’s Hospital. "You have no native immunity to measles so that allows it to multiply rapidly," Nachman said.

Additionally, "measles is still rampant outside the U.S. and we have a lot of travelers," Nachman said. "Measles is highly contagious and for those travelers who are undervaccinated or not vaccinated, they are always at risk."

Nachman said she believes there is "significant undercounting" of measles cases because some people who are infected don’t seek testing.

How many cases have there been in New York this year?

There have been six confirmed cases in New York City, four in Orange County, one in Suffolk County, one in Ontario County and one in Putnam County, according to the state Health Department. The Suffolk case was an infant who had contracted the disease while traveling and was too young to be vaccinated.

There were 15 cases in the state in 2024: 14 in New York City and one in Nassau County. The Nassau patient was an unvaccinated child under age 5 who had not traveled abroad, officials said. Both Long Island children recovered.

In 2000, measles was declared eliminated in the U.S. Has that changed?

"Eliminated" means the "absence of the continuous spread of disease was greater than 12 months," according to the CDC. At that point, there had been less than 1,000 cases every year since 1993.

Dr. Matthew Harris, a pediatric emergency medicine physician at Cohen Children's Medical Center in New Hyde Park, said even though there has been no official announcement from federal health officials, it seems clear measles is no longer technically eliminated in the United States.

He said, "If we don't get ahead of this, every year we're going to have a spike of measles. And we'll have deaths from a vaccine-preventable illness."

Are fewer children getting the measles, mumps and rubella vaccine?

Yes. The CDC has reported that between the 2019-2020 and 2022-2023 school years, the number of kindergarten students across the nation who received state-required vaccinations — including the MMR vaccine — declined from 95% to about 93%. The number of exemptions to vaccines also went up to 3.3% from 3.0%, and increased to 5% in some jurisdictions.

In New York, about 81.2% of children between 24 and 35 months received their first MMR dose by age 2. In Nassau County, it was 82%, and 82.6% in Suffolk County.

Both Nachman and Harris urged people to make sure their children receive the measles, mumps, rubella (MMR) vaccine on the recommended schedule, which is the first dose between 12 and 15 months and the second dose between ages 4 and 6.

"This is a very safe vaccine that’s been around for almost 60 years," Harris said. "Measles can be a devastating disease and you can't undo it."

Should people in New York and on Long Island be concerned?

Even though the number of cases in New York is low compared with other regions, Nachman pointed out that measles is a virus that can cause serious illness and death, and that is always a concern. But it is also preventable.

"That means getting my vaccine, getting my kids vaccinated and my grandkids vaccinated," she said.

She also pointed out that a percentage of people who get measles can see its effects years later, such as developing subacute sclerosing panencephalitis (SSPE), an often fatal neurological condition.

"We have to recognize that this is the biggest surge in over 30 years," Harris said of the outbreak.

He said the nationwide decline of fully vaccinated eligible kindergartners from 95% to 93% "may not sound like a significant decline, but you need to have somewhere around 96-97% to have significant herd immunity. This is just getting us farther and farther away from being safe."

By Lisa L. Colangelo

lisa.colangelo@newsday.com@lisalcolangelo

Lisa joined Newsday as a staff writer in 2019. She previously worked at amNewYork, the New York Daily News and the Asbury Park Press covering politics, government and general assignment.