CDC warns of spike in US measles cases
Nearly a third of all U.S. measles cases in the past four years happened during a three-month stretch in 2024, according to a report from the Centers for Disease Control and Prevention.
The rise in measles is troubling. Officials attribute it to the drop in the U.S. vaccination rate for the deadly and preventable virus amid a global surge in cases. For now, the risk of widespread transmission remains low due to existing immunity and robust public health responses to contain outbreaks, according to the report published Thursday.
The CDC documented nearly 340 measles cases since January 2020. Almost 100 of the infections happened in 2024, prior to March 28, with cases occurring in more than a dozen states. Since then, there have been more than a dozen cases so far in April that aren’t included in the report.
At the start of the year, the CDC warned clinicians about signs of the virus amid the global uptick. The latest report mostly blames unvaccinated U.S. residents who traveled abroad and brought measles home to schools or hospitals they visited. The scourge of measles was once thought to be a thing of the past. Public health officials in 2000 declared measles had been eliminated in the U.S. after decades of people taking vaccines, which are highly effective at preventing the virus.
Since that 2000 declaration, many Americans have chosen not to vaccinate their children, which CDC officials said contributed to the recent outbreaks. The median age of a measles patient is 3. About 90% of the new cases presented in patients who were not vaccinated or for whom vaccination status was unknown.
“This is akin to turning back the clock to the bad old days,” Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, told USA TODAY.
Before vaccines, Schaffner said, between 400 and 500 people died annually of the disease. Measles leaves about one-fifth of children hospitalized and about 1 in 1,000 with brain swelling. Of 1,000 children who contract the disease, 1 to 3 will die.
Recent cases, Schaffner said, are a consequence of parents delaying routine measles, mumps and rubella vaccinations, or withholding the vaccines altogether from their children, which are typically required at U.S. public schools.
“The only way it can come back is if we stop vaccinating and permit virus in other parts of the world to be imported into the United States and then spread,” he said.
The CDC report confirmed nearly all the cases were introduced from abroad by people entering the U.S. from other regions, primarily from what the World Health Organization defines as Eastern Mediterranean and African regions.
U.S. residents traveling abroad accounted for two-thirds of imported cases, although the report noted that imported cases were likely underreported.
Despite pundits who’ve cast blame, the data does not indicate that migrants brought the measles in from the southern U.S. border. Public health officials said the outbreak this year at a Chicago migrant shelter, for example, likely started through local transmission.