Measles Returns to San Francisco With First Confirmed Case Since 2019

Unvaccinated infant diagnosed with the highly contagious disease after travel abroad

Apr. 16, 2026 at 8:43pm by

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A ghostly, translucent X-ray photograph showing the internal structures of a measles virus particle, with its intricate details and shapes glowing against a dark background.An X-ray view of the measles virus reveals the intricate details of this highly contagious pathogen.San Francisco Today

San Francisco health officials have confirmed the city's first measles case in seven years after an unvaccinated infant under 12 months old was diagnosed with the disease. The infant was exposed to measles in another country and became ill after returning to San Francisco, though the child is now recovering at home. Public health workers are tracing additional exposures, but experts say the risk to the general public remains low due to the city's high vaccination rates.

Why it matters

Measles is a highly contagious airborne disease that can lead to serious complications, especially in young children. This case highlights the continued vulnerability of unvaccinated infants and the importance of vaccination, as measles cases rise nationally due to factors like vaccine hesitancy and missed immunizations during the COVID-19 pandemic.

The details

The infant is the first person to be diagnosed with measles in San Francisco since 2019. The child was exposed to the disease while traveling abroad and became ill after returning to the city. All of the infant's household contacts report being vaccinated. Public health officials are working to identify and notify any additional people who may have been exposed.

  • The infant was diagnosed with measles on April 12, 2026.
  • This is the first confirmed measles case in San Francisco since 2019.

The players

Dr. Peter Chin-Hong

A UCSF infectious disease expert who emphasized that the risk to the general public remains low due to San Francisco's high vaccination rates.

Dr. Susan Philip

The San Francisco Health Officer who urged the importance of getting the MMR vaccine to protect against measles, one of the most infectious diseases in the world.

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What they’re saying

“Infectious disease doesn't respect any borders.”

— Dr. Peter Chin-Hong, UCSF infectious disease expert

“It is incredibly important to get the MMR vaccine, as measles is one of the most infectious diseases in the world.”

— Dr. Susan Philip, San Francisco Health Officer

What’s next

Public health workers are continuing to trace any additional exposures related to the confirmed measles case.

The takeaway

This case serves as a reminder of the ongoing need for vaccination, especially for vulnerable populations like unvaccinated infants, as measles cases rise nationally. San Francisco's high vaccination rates have so far prevented broader spread, but the city must remain vigilant to protect the community.