Hepatitis A Outbreak in California
Final update as of April 11, 2018.
With the slowdown in reported hepatitis A cases across California, CDPH has demobilized the outbreak response and continues to monitor reported hepatitis A cases statewide. While CDPH might receive additional reports of outbreak-associated hepatitis A cases, CDPH has entered a new phase where monitoring of cases and prevention activities, such as vaccinating the at-risk population (people experiencing homelessness and/or using illicit drugs in settings of limited sanitation), have been shifted from emergency response to day-to-day operations. CDPH greatly appreciates the monumental efforts of federal, state, and local government partners, especially local public health departments and their community partners, as well as private partners, to control this large hepatitis A outbreak. We encourage partners to continue providing hepatitis A vaccination for people experiencing homelessness, along with other high-risk groups, including people using illicit drugs and men who have sex with men.
Below is a summary of the outbreak and CDPH response as of April 11, 2018. Any subsequent hepatitis A cases reported to CDPH will be included in our annual surveillance reports.
No future website updates of this page are planned.
The outbreak began in San Diego County in November 2016 and spread to Santa Cruz, Los Angeles, and Monterey counties. To date, San Diego and Santa Cruz have reported the greatest number of cases, and in addition to cases in Los Angeles and Monterey counties, other counties have reported 17 outbreak-associated cases. The majority of people who have been infected with hepatitis A virus in this outbreak are people experiencing homelessness and/or using illicit drugs in settings of limited sanitation. Other states are experiencing outbreaks in similar populations of at-risk people. Following intensive efforts by local health departments and their clinical and community partners, including vaccination campaigns targeting the at-risk population, education, obtaining and managing vaccine, and many other interventions, the number of reported outbreak-associated cases has substantially decreased in California.
CDPH has helped to support the local health department response in the following ways:
- Coordinating and supporting hepatitis A outbreak response efforts across California and supporting the Governor's declaration of a state of emergency to secure and purchase vaccine in a time of vaccine constraint.
- Monitoring the outbreak and providing epidemiologic support to the response by enhancing monitoring of cases, testing specimens to identify the outbreak strain, and providing staff and technical expertise, including developing and disseminating disease control, clinical, and vaccine prioritization guidance.
- Buying, distributing, and monitoring hepatitis A vaccine – to date, CDPH has distributed about 123,000 vaccine doses to local health departments during this outbreak.
- Communicating accurate information about the outbreak, control measures, and level of risk of hepatitis A infection for different populations with partners, the media, and the public.
For more information about preventing Hepatitis A, visit the
CDC website or visit our
Hepatitis A disease page.