At least 125 measles cases have been reported across 17 states so far this year, the Centers for Disease Control and Prevention said Friday, up from 121 cases last week.
More cases have now been reported this year than in all of 2022, the most recent annual peak of measles infections. Cases of measles had surged that year from outbreaks linked to unvaccinated Afghan refugees.
Illinois remains the state with by far the largest number of measles cases this year, after a large outbreak at a Chicago migrant shelter that the city's health department now says has slowed significantly in the wake of a major vaccination push.
Massimo Pacilli, a deputy commissioner for the Chicago Department of Public Health, acknowledged CDC reports of higher rates of fully vaccinated people catching measles during the outbreak, which he chalked up to intense spread of the virus within the densely packed shelter.
"In this setting, we're observing continuing protracted exposures. And so it is not completely unexpected to see a higher proportion of individuals who may have had a dose end up being infected with measles," said Pacilli.
The recent announcement from the CDC highlighted the concerning trend of "importations" of the measles virus by unvaccinated international travelers, posing a new threat to the U.S.'s previously achieved status of eliminating local spread of the virus back in 2000.
Back in 2019, officials had expressed concerns about the potential loss of the elimination status, as evidenced by monthslong outbreaks in New York that led to a record 1,274 cases that year — the highest number since the 1990s.
While the CDC does not anticipate this year's case totals to surpass those of 2019, they are mindful of the increasing risk of outbreaks.
According to the agency's disease forecasters, there is an estimated likelihood of the U.S. reaching 300 measles cases this year, a number higher than recent years.
"It's crucial to bear in mind that while the overall measles outbreak risk to the general population remains low, the global increase in measles cases raises the possibility of importations into the U.S. and subsequent outbreak risks, especially in communities with low vaccination rates," emphasized the agency's forecasters.
