Measles Outbreak Confirmed in Sacramento Area with Exposure at Pediatric Care Location

Sacramento and Placer Counties confirmed a measles outbreak with 11 and 8 cases respectively, part of 39 total California cases in 2025, representing a sharp increase from 15 cases in all of 2024. Ten of Sacramento County's 11 cases involved people with no vaccination records, and 37 of California's 39 cases were either unvaccinated or had unknown status. Exposure occurred at a Sacramento pediatric care location, raising concerns given measles' extreme contagiousness—one infected person can spread it to about 15 others, and the virus lingers in air for two hours. Health officials stress the MMR vaccine provides over 99% protection and urge unvaccinated people to reconsider group activities.

Outbreak Scale and Vaccination Status of Cases

• ▪California confirmed 39 measles cases in the state as of 12 p.m. Monday this year
• ▪A pediatric care setting in Sacramento County was exposed to measles
• ▪Two measles cases in California led to hospitalizations
• ▪Ten of the 11 measles cases in Sacramento County had no vaccination records
• ▪Sacramento County reported 11 measles cases in the ongoing outbreak
• ▪California Department of Public Health reported 25 confirmed measles cases in 2025
• ▪Of the 39 California measles cases, 37 people were either unvaccinated or their vaccination status was unknown

Extreme Contagiousness and Transmission Characteristics of Measles

• ▪Measles can linger in the air for up to two hours after an infected person leaves a room
• ▪One person infected with measles can infect about 15 people
• ▪One person infected with COVID-19 can infect four to five people
• ▪Measles can spread without the infected person being in the same room as others
• ▪Measles is one of the most contagious diseases in the world, especially among children

Public Health Response and Prevention Measures

• ▪Vaccination is the most effective way to prevent measles infection
• ▪Northern California health officials held a news conference about the ongoing measles outbreak with Dr. Olivia Kasirye, Dr. Robert Oldham, Dr. Dean Blumberg, and Dr. John Belko
• ▪Dr. Robert Oldham urged unvaccinated people to reconsider group activities due to the measles outbreak
• ▪Sacramento County and Placer County plan to provide weekly updates on measles case numbers
• ▪The MMR vaccine provides more than 99% protection against measles for people who are fully vaccinated

Perspective of Sacramento and Placer County health officials

• ▪Dr. Robert Oldham urged unvaccinated people to reconsider group activities due to the measles outbreak
• ▪Sacramento County and Placer County health officials view vaccination as the most effective way to prevent measles infection

Perspective of Unvaccinated or under-vaccinated populations

• ▪Unvaccinated individuals in Sacramento and Placer Counties face exposure risk at pediatric care settings where measles was present
• ▪People with unknown vaccination status in California account for a significant portion of the 39 measles cases reported in 2025