Los Angeles County child dies from rare measles complication years after infant infection

Los Angeles County health officials announced Thursday that a school-age child has died from subacute sclerosing panencephalitis (SSPE), a rare, progressive brain disorder that can develop years after a measles infection. The child had contracted measles as an infant before becoming eligible for the measles, mumps and rubella (MMR) vaccine; the county did not release the child’s age, sex or the timing of the initial infection.

County health officials said the child recovered from the initial measles infection but later developed SSPE, which causes progressive neurological deterioration and is fatal in the vast majority of cases. "This is a painful reminder of how dangerous measles can be, especially for our most vulnerable community members," Los Angeles County Health Officer Dr. Muntu Davis said in a statement, adding that "infants too young to be vaccinated rely on all of us to help protect them through community immunity."

SSPE is caused by the persistence of the measles virus in the central nervous system after the initial infection. It typically appears several years later and leads to symptoms that can include intellectual decline, personality changes, seizures, involuntary movements and, ultimately, a vegetative state. There is no cure; treatment focuses on supportive care and anticonvulsant medications, and the disease is fatal in about 95 percent of cases. Public health authorities estimate SSPE occurs in roughly one in 10,000 unvaccinated people who contract measles, and about one in 600 among those infected as infants.

The MMR vaccine is routinely administered in two doses, with the first recommended between 12 and 15 months of age and a second between ages four and six. The two-dose regimen is about 97 percent effective in preventing measles. California’s kindergarten vaccination coverage for two MMR doses is reported by the Centers for Disease Control and Prevention at about 96 percent, just above the roughly 95 percent threshold commonly cited as needed for herd immunity. Nationwide, CDC data show that 92.5 percent of kindergarteners in the 2024–2025 school year were fully vaccinated for measles, mumps and rubella.

Public health officials have raised concerns about declining vaccination coverage as the United States confronts a large measles outbreak in 2025. The CDC has confirmed 1,454 measles cases across 42 states so far this year, the majority of them in Texas, which reported 803 cases; California has reported 20 cases. Prior to this Los Angeles County announcement, health agencies reported three deaths this year linked to measles — one in Colorado and two children in Texas.

Measles is a highly contagious viral illness that typically causes fever, cough, runny nose, red eyes and a characteristic rash. Patients are contagious from about four days before the rash appears through four days after. Unvaccinated people who share the same air as an infected person, even briefly or hours later, have a high risk of infection; authorities say unvaccinated persons have about a 90 percent chance of becoming ill if exposed. Severe complications of measles include pneumonia, acute encephalitis (brain swelling) and permanent brain damage; roughly three in 1,000 people who contract measles die from the infection or its complications.

Before the two-dose vaccine became available in 1968, measles caused hundreds of deaths and tens of thousands of hospitalizations annually in the United States. Public health agencies say the rarity of measles in recent decades is the reason SSPE is now uncommon: the CDC estimates no more than about 10 SSPE cases are reported in the United States each year.

Los Angeles County health officials reiterated their appeal for vaccination to protect vulnerable groups, including infants who are too young to receive MMR, pregnant people and those with weakened immune systems. "By getting vaccinated, individuals not only protect themselves but also help shield vulnerable populations," the county statement said. The announcement did not provide additional details about the child’s identity or the clinical timeline leading to the SSPE diagnosis and death.