The CDC has raised alarms that measles, an infectious disease once declared eliminated in the U.S. in 2000, is at risk of reemerging due to increasing outbreaks. In early 2024, there were 97 reported cases of measles, marking a significant increase from the average five cases reported annually in the first quarters of 2020 through 2023. This recent spike accounts for 29% of the 338 total cases identified between January 2020 and March 2024.
A concerning 68% of these cases were among unvaccinated individuals, with the vaccination status of another 23% remaining unknown. Only 9% of those infected had received at least one dose of the measles-mumps-rubella (MMR) vaccine. The majority of infections were in young people aged between 16 months and 19 years.
International travel significantly contributed to the spread, with 96% of the 338 cases linked to measles imported from abroad, particularly from the Eastern Mediterranean and African regions. There has also been a notable increase in cases imported from Europe and South-East Asia, rising to six cases from each region in the first three months of 2024.
Despite being declared eliminated nearly 25 years ago, measles poses a threat to approximately 250,000 unvaccinated kindergarten-age children in the U.S., undermining herd immunity which remains below the Healthy People 2030 target of 95% coverage.
The threat to the U.S.’s measles-free status is intensified by a global increase in measles cases and falling vaccination rates, both domestically and globally. Notably, in 2019, New York and New York City saw prolonged outbreaks in under-vaccinated communities, nearly compromising the country’s elimination status from 2001 to 2019.
More recently, in 2022, Central Ohio faced an outbreak where 94% of those affected were unvaccinated, with 42% requiring hospitalization. In February 2024, an outbreak at Manatee Bay Elementary School in Florida prompted state health officials to echo CDC recommendations that unvaccinated individuals stay home, though the final decision was left to parents or guardians.
