San Bernardino County health officials have reported the county's first measles case since 2023.
In a news release shared on Friday, the San Bernardino County Department of Public Health said that an unvaccinated minor who was visiting California from another state was infectious when they visited the Walmart Supercenter located at 1333 Mountain Avenue in Ontario on Jan. 29, 2026 between noon and 3 p.m.
Officials said that the incident is not connected to a pair of recent cases involving Disneyland visitors. It's now at least the seventh case reported in Southern California, as both Orange and Los Angeles counties have confirmed three cases each.
"Vaccines are our best defense against infectious diseases, protecting both individuals and the wider community," said a statement from San Bernardino County Health Officer Dr. Sharon Wang. "Staying healthy and staying up to date with vaccinations is a key step to safeguarding public health and saving lives."
Officials said that people who visited the store during the identified timeframe could be at risk of developing measles, especially if they are unvaccinated, immunocompromised or pregnant.
Measles is a highly contagious virus that spreads through the air when an infected person coughs, sneezes or talks, health officials said. Symptoms typically develop between seven and 21 days and include fever, cough, red eyes and a runny nose, followed by a rash that begins on the face and spreads to the body. People sick with measles are contagious from four days before the onset of the rash to four days after.
"Measles is not just a rash and fever," the release said. "Measles can lead to serious health complications, including ear infections, lung infections, diarrhea, and in rare cases, brain swelling or death."
Health officials urged anyone who feels ill or believes they have been exposed to contact their healthcare provider immediately.