The number of confirmed measles cases in the U.S. so far this year has hit 2,318, surpassing the total reported for all last year, according to data updated Friday from the Centers for Disease Control and Prevention.

Previously, last year’s total of 2,289 was the highest number of recorded measles cases in more than 30 years, CDC data shows. The new figure marks the highest number of cases recorded since 1991.

Cases have been confirmed in 43 states and the District of Columbia. Sixteen of this year’s total have been among international visitors to the U.S., according to the CDC.

The majority of measles cases in 2026 have been confirmed among children and teenagers aged 19 and younger, according to the CDC. About one in 10 children under age 5 have been hospitalized.

About 93% of cases are among people who are unvaccinated or whose vaccination status is unknown, CDC data shows.

Meanwhile, 3% of cases are among those who have received just one dose of the measles, mumps, rubella (MMR) vaccine and 4% of cases are among those who received the recommended two doses, according to the CDC.

“Crossing this threshold is a tragic reminder that measles has made an alarming comeback in the United States,” Dr. Richard Besser, former acting CDC director during the Obama administration, said in a statement to ABC News. “As a pediatrician and a parent, it breaks my heart that so many children are suffering needlessly from a dangerous and potentially fatal disease that vaccines can prevent. It represents a profound moral failure on the part of our national health leaders.”

The CDC currently recommends that people receive two doses of the MMR vaccine, the first at ages 12 to 15 months and the second between 4 and 6 years old. One dose is 93% effective, and two doses are 97% effective against measles, the CDC says.

However, CDC data shows vaccination rates have been lagging in recent years. During the 2024 to 2025 school year, 92.5% of kindergartners received the MMR vaccine, according to data. This is lower than the 92.7% seen in the previous school year and the 95.2% seen in the 2019 to 2020 school year, prior to the COVID-19 pandemic.

Some public health specialists previously told ABC News they believe the U.S. is on track to lose the elimination status it earned in 2000.

The specialists said there are several reasons for the U.S. breaking measles case records for the second year in a row, including declining vaccination rates, people not fearing the measles virus, a loss of trust in public health institutions and a perceived lack of clear guidance and communication from the nation’s top public health officials.