A second confirmed case of the mumps was reported at Berkeley High School on March 4, 2026. Credit: Elsie Yuen Credit: Elsie Yuen
Berkeley health officials issued a moderate-risk mumps exposure alert for Berkeley High School (BHS) on Wednesday after confirming a second case on campus that is believed to have been spread through direct contact.
In late February, officials reported that people at BHS and Sylvia Mendez Elementary were potentially exposed to mumps earlier that month and in mid-January, but the risk of community transmission at that time was considered “very low.” The second reported case at BHS prompted Berkeley’s public health department to increase its risk assessment for exposure on campus.
The latest mumps case at BHS is linked to a person who was on campus while sick on Feb. 19 and 20, according to an email from Principal Juan Raygoza to the school community on Wednesday. Berkeley Unified School District (BUSD) officials declined to say whether the individual is a student or staff member, and did not disclose their vaccination status.
BUSD families were urged to monitor symptoms through March 17 and keep sick kids at home. Officials advised BHS community members to avoid sharing utensils and drinks to prevent further spread. City health officials recommend the BHS community confirm vaccination status, “and, if needed, complete vaccination.”
Berkeley Public Health and the school district are monitoring the situation “closely” to reduce the risk of transmission. In an email statement Thursday afternoon, BUSD said city health officials are offering “prevention and response strategies” at BHS and are conducting “enhanced surveillance” and testing guidance to detect any additional cases.
Mumps symptoms can include cheek or jaw swelling, fever, headache, muscle pain, fatigue and pain near the ears and neck. Officials said the virus may be contagious before symptoms appear, which can be about 12 to 25 days after exposure.
At Berkeley High, students and teachers express a mix of surprise and concern
Talia Nishioka, a senior at BHS, said the spread of the virus through direct contact at BHS might mean that “it’s going to become a bigger thing.”
“I normally get extremely worried about sicknesses going around,” she said. “I was actually super concerned until my dad told me that I have a vaccine, so I’m kind of chill now.”
BHS math teacher Anna Shim said she was “shocked and disturbed” when she received the mumps exposure notification. She had noticed kids out sick recently, but does not know if any of her students were affected by the virus.
“I just thought it was a cold going around,” she said.” I feel like a lot of kids have been out sick longer with a really long, nasty fever. One kid was out for like two weeks.”
June Griffith, a Berkeley High junior, said she had not heard of the mumps virus until BHS sent out the exposure notice. She said she’s not too worried because she is vaccinated, but the possibility of contracting the disease is “scary and unknown.”
“I think most of my friends have brought it up to me today, saying that it’s weird … and out of the blue,” she said on Thursday.
Local mumps cases come on the heels of national rise in anti-vaccine rhetoric
BUSD and the local public health department said “vaccination remains the strongest protection” and recommended masking for people experiencing symptoms. Raygoza’s message to the school community noted that vaccinated people are less likely to develop severe illness, but can still spread the virus through coughing, sneezing, and saliva.
“If the other kids at Berkeley High School have been immunized, the chances of them coming down with mumps, even if they were exposed, are very small,” UC Berkeley Health Sciences Clinical Professor Emeritus John Swartzberg told Berkeleyside.
He said, however, that immunity from the two‑dose measles, mumps, and rubella (MMR) vaccine can decline after about a decade, meaning a vaccinated child may have reduced protection by the time they are teenagers.
California schools are required to verify MMR vaccination at the kindergarten and 7th-grade levels. The state has among the highest MMR vaccination rates in the country, at 95% for all entering kindergarteners.
All 11 BUSD elementary schools reported MMR vaccination rates at 90% or above, according to an April data map by EdSource. Experts say that at least 95% of students should be vaccinated to maintain herd immunity and prevent outbreaks.
City officials said in an email Thursday afternoon that 7th-grade BUSD vaccination data “would not necessarily reflect” the current population at Berkeley High, as new students enroll and others move away.
Swartzberg said the mumps virus is not as contagious as COVID-19 or measles. He said a “moderate” risk indicates “that you may have spent some time in close proximity” with an infected person. He added that a person with mumps is contagious up to about 48 hours before symptoms show and at least five days after.
The recently reported mumps cases and possible exposures at BUSD come amid increased anti-vaccine activism nationally, fueled by misinformation and confusion about the efficacy of vaccines, and belief in the unfounded claim that some vaccines may cause autism.
The mumps cases at Berkeley High also come amid a surge in measles cases nationally. While measles is a distinct virus, it is in the same family of Paramyxoviridae viruses, and can be prevented by the same MMR vaccine. There were 2,281 confirmed cases of measles in the U.S. last year, according to the Centers for Disease Control, the highest number in over three decades.
“Unfortunately, there’s a direct relationship between the percentage of people protected with the vaccine and the number of cases we’re going to see — and those (vaccine) numbers are dropping,” Swartzberg said. “We have a concerted push by the United States government to discourage vaccination in every way they can.”
Swartzberg said he had mumps as a child “long before the vaccines were available.” He described the experience as “miserable,” and though he got better, some severe cases can lead to organ damage, hearing loss, and sterility.
“These diseases are preventable. Protect children with immunization, it’s as simple as that,” he said.
Before the February alert, the most notable mumps outbreak in Berkeley occurred in 2011, afflicting 20 UC Berkeley students and requiring mass booster shots. At the time, Berkeleyside reported that a significant number of city residents were not vaccinated against the virus. Before that outbreak, Berkeley had seen only six reported mumps cases since 1990.
“Regardless of who the cases are, the exposure risk at Berkeley High is the same for everyone. However, the risk of severe symptoms is greatly reduced by having both MMR shots,” City spokesperson Matthai Chakko said in an email Thursday afternoon.
Contributing reporter Rigzin Gyaltsen writes for The Berkeley High Jacket, a student-run publication.
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