As the U.S. faces a growing measles outbreak, the infection prevention and control (IPC) team at Alameda Health System (AHS) serves as our first line of defense by keeping staff informed about the risks, promoting vaccination, implementing education programs, and using surveillance to track potential exposures. Their proactive efforts help protect the health of our patients, staff and community.
“Our goal is to prevent infections before they occur,” said Deborah Ellis, Ph.D., system director of infection prevention and control. “We’re constantly monitoring for potential threats of contagious diseases like measles, educating staff and reinforcing protocols to ensure that everyone knows how to respond effectively.”
Under Dr. Ellis’ direction the IPC team has maintained active surveillance of measles since the initial outbreaks in Texas and New Mexico earlier this year.
According to Dr. Ellis, the highly contagious measles virus can remain airborne for at least two hours, within a room, infecting up to 90% of unvaccinated people exposed. Symptoms, such as rash, fever, cough and runny nose usually develop seven to 14 days after exposure.
The Centers for Disease Control and Prevention (CDC) has confirmed 483 measles cases in the first three months of 2025, a sharp increase from the 285 cases reported throughout 2024. As of March 27, 2025, 483 of this year’s cases have been identified in 20 states, including California where the California Department of Public Health (CDPH) confirmed eight measles cases in San Mateo, Fresno, Los Angeles, Orange, Placer, and Tuolumne Counties, mostly linked to international travel and unvaccinated individuals.
The Bay Area’s fluctuating immunization rates is especially concerning . While some counties have improved their measles, mumps, and rubella (MMR) vaccination coverage in recent years, CDPH reports others have seen declines. Of the measles cases reported, approximately 98% have involved people who were unvaccinated or had an unknown vaccination status.
In Alameda County, MMR rates have dropped by nearly a percentage point over the past two years, while neighboring San Francisco and Contra Costa Counties have made modest gains. These rates leave certain areas more vulnerable to outbreaks, underscoring the need for consistent vaccination efforts.
“The most powerful weapon against measles is vaccination, which is 97% effective at preventing the development of the disease,” said Dr. Ellis. “We can’t outsmart the germs, but we can outsmart measles with vaccination — it’s our best defense.”
And while the measles vaccine offers strong protection, surveillance is key to early outbreak detection — driven by real-time data sharing between Alameda County, neighboring counties, the State and the CDC. This helps the IPC team track the outbreak both locally and nationally to identify the risks early for prevention planning.
A self-proclaimed “germ detective,” Dr. Ellis and her team share a common purpose and passion for the investigative aspects of infectious diseases. “Tracking infectious diseases is the ultimate puzzle — gathering clues, identifying patterns and finding solutions to protect public health,” she said.
For more information on measles prevention and vaccination guidance and visit the California Department of Public Health.