State of California—Health and Human Services Agency
California Department of Public Health

Health Alert

To: Healthcare Professionals

Increase of Measles in California

2/4/2026

Key Messages

An increase in measles cases has been confirmed in California in recent weeks, with six cases being reported in the last week.
Health care providers should consider measles in persons presenting with a fever, rash, and other symptoms consistent with measles.
Airborne precautions should be immediately instituted to prevent nosocomial measles exposures.
Suspected measles cases should be promptly reported to the appropriate local health department (LHD) by telephone, even before laboratory confirmation.
Ensure all patients, especially those planning international travel, are up to date on MMR vaccine per CDPH recommendations.

Background

As of January 29, 2026, 588 confirmed measles cases in the United States, mostly from northern South Carolina, had been reported to the Centers for Disease Control and Prevention (CDC) in 2026. As of February 2, 2026, nine confirmed measles cases have been reported in California in 2026, six of whom were associated with international travel. None have had documentation of immunization with MMR vaccine. Direct importations of measles by international travelers and from areas of the United States experiencing large measles outbreaks are expected to continue. Delays in identifying and isolating patients with measles in health care settings can result in exposures to hundreds of contacts.

CDPH Recommendations

Suspect measles in patients with:

Fever, rash and any of the “3 Cs" – cough, coryza, or conjunctivitis
In the prior 3 weeks, any of: attendance of an event or location with a known measles exposure, international travel, transit through airports, or potential interactions with international visitors at theme parks or other settings in the U.S.

Steps for providers to take when patients present with fever and rash:

Mask the patient immediately, if possible.
Bypass the waiting room: Keep the patient out of common areas.
Isolate patient immediately, in an airborne infection isolation room (AIIR) if possible. See CDC and CDPH (PDF) infection control guidance. People with measles are contagious from 4 days before rash onset through 4 days after rash onset.
All healthcare personnel entering the patient room, regardless of immune status, should use respiratory protection at least as effective as a FIT-tested N95 respirator, per Cal/OSHA requirements.
Assess for risk factors and measles immunization status.
Promptly telephone the local health department (LHD) to report suspected measles cases, even before laboratory confirmation, to discuss measles testing and control measures.
Collect throat or NP swab and urine for polymerase chain reaction (PCR) testing. See Measles testing guidance. PCR is the preferred method for diagnosis and public health laboratories are the preferred setting for testing. Sending samples to commercial labs and not notifying public health of suspect cases can result in significant delays in diagnosis and infection prevention measures.

Importance of immunization: Ensure all patients are up to date on MMR vaccine.

CDPH recommendations for patients planning international travel:

Infants 6 to 11 months old: 1 early dose of MMR vaccine, followed by 2 doses after the first birthday.
Children 12 months and older: 2 doses of MMR vaccine. The second dose may be given as soon as 28 days after the first dose.
Adults born during or after 1957 without evidence of immunity against measles: Documentation of 2 doses of MMR vaccine at least 28 days apart.