(CNN) - There have been 971 cases of measles reported in the United States this year, the US Centers for Disease Control and Prevention said Thursday.
This means 2019, which is not quite half over, now has the greatest number of cases in a single year in nearly three decades.
The number of cases in 1994 was 963, which was lower than in 1992 when there were 2,237 cases.
"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. Again, I want to reassure parents that vaccines are safe, they do not cause autism. The greater danger is the disease that vaccination prevents," said CDC Director Dr. Robert Redfield.
Measles was eliminated in the United States in 2000, meaning it was no longer continuously transmitted in the country.
Cases have been reported in 26 states this year so far.
New York has been the largest contributor to this year's unfortunate milestone with nearly 700 cases of measles reported this year in the state. Most of those cases have been in Orthodox Jewish communities with low vaccination rates.
Clark County in Washington state had the second-largest outbreak in the US this year with more than 70 cases reported. The county has low vaccination rates.
"If these outbreaks continue through summer and fall, the United States may lose its measles elimination status. That loss would be a huge blow for the nation and erase the hard work done by all levels of public health. The measles elimination goal, first announced in 1966 and accomplished in 2000, was a monumental task," the agency said in statement. "Before widespread use of the measles vaccine, an estimated 3 to 4 million people got measles each year in the United States, along with an estimated 400 to 500 deaths and 48,000 hospitalizations."
The elimination of the virus in the United States is attributed to widespread measles, mumps and rubella vaccination and a "strong public health infrastructure to detect and contain measles," according to the CDC.
"Your decision to vaccinate will protect your family's health and your community's well-being," Redfield said. "CDC will continue working with public health responders across our nation to bring this outbreak to an end."
The cases in the Unites States are imported from international travel and then local outbreaks begin when the highly contagious illness spreads to those who are not immune to the virus from vaccination or having recovered from measles. With the busy summer travel season just about to get underway there's concern about continued importation of measles among vacationers.
In communities with 95% or more of residents who are vaccinated against the virus, herd immunity works. That's when unvaccinated people are protected because so many of those around them are.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases told lawmakers earlier this year that more needs to be done.
"I consider it an irony that you have one of the most contagious viruses known to man juxtaposed against one of the most effective vaccines they have," Fauci said. "Yet we don't do and have not done what could be done - namely eliminate eradicate the virus."
Correction: A quote from the CDC in a previous version of this story incorrectly stated the year when the measles elimination goal was announced. CNN's John Bonifield contributed to this report
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