• Posted April 12, 2024

Spike in Measles Cases Could Threaten Elimination Status in U.S.: CDC

More than 100 measles cases have already been reported in the United States this year, a significant increase over previous years that threatens the country's attempts to eliminate the illness, federal health officials warned Thursday.

A total of 338 measles cases were diagnosed in the United States from January 2020 through March 2024, with 97 of those cases reported in 2024 alone, a new study from the U.S. Centers for Disease Control and Prevention found. That represents a more than 17-fold increase over the mean number of cases reported during the first quarters of 2020–2023.

And cases have continued to climb since then: CDC data shows a total of 113 measles diagnoses as of April 4.

“The U.S. measles elimination status will continue to be threatened by global increases in measles incidence and decreases in global, national and local measles vaccination coverage,” researchers wrote in the report published April 11 in the CDC publication Morbidity and Mortality Weekly Report.

“Risk for widespread U.S. measles transmission remains low because of high population immunity,” noted researchers led by Adria Mathis, from the CDC's Division of Viral Diseases. “However, because of the increase in cases during the first quarter of 2024, additional activities are needed to increase U.S. routine measles, mumps and rubella vaccination coverage, especially among close-knit and under-vaccinated communities. These activities include encouraging vaccination before international travel and rapidly investigating suspected measles cases.”

Targeting the unvaccinated is indeed critical, the statistics show.

Of the infections reported this year, 83% have been in unvaccinated people and another 12% only had one dose of the two-dose vaccine, the latest CDC data shows. Half of cases have been in children younger than 5, and nearly 60 percent of people -- including two thirds of children younger than 5 -- have been hospitalized.

The vast majority of cases (96%) were associated with international travel, and most of those cases (61%) occurred among U.S. residents who were not vaccinated despite being eligible, or whose vaccination status was unknown, the CDC report showed.

Imported cases are expected, but vaccination coverage is key to ensuring outbreaks don't persist in the United States, experts said.

“Maintaining measles elimination status is an important public health benchmark. Public health jurisdictions are reaching out to communities and populations with low vaccination rates and we feel this approach will be effective. However, the increase in misinformation about measles vaccination undermines these efforts and could ultimately endanger our elimination status,” Dr. Marcus Plescia, chief medical officer of the Association of State and Territorial Health Officials, told CNN.

Just last month, the CDC issued a health alert to doctors, urging them to vaccinate infants a few months ahead of the typical schedule if families are planning to go abroad.

Measles is a highly contagious airborne disease that can cause serious health consequences or death, especially for young and unvaccinated children, the CDC says.

General symptoms may include fever, cough, runny nose, watery eyes and a rash of red spots. About 1 in 5 unvaccinated people who get measles will be hospitalized, according to the CDC, while up to 3 of every 1,000 children who become infected with measles may die from respiratory and neurological complications.

Because measles is so contagious, a high level of vaccination coverage is key to minimizing spread, experts say. The United States has set a target vaccination rate of 95%, but coverage among kindergarteners has dipped below that in recent years.

In the 2022-23 school year, just 93.1% of kindergarteners had completed their measles vaccine doses, CDC data shows, leaving about 250,000 at risk.

More information

The U.S. Centers for Disease Control and Prevention has more on the measles.

SOURCE: Morbidity and Mortality Weekly Report, April 11, 2024; CNN