Public health officials in Berkeley, California, are investigating potential mumps exposures at two schools – Berkeley High School and Sylvia Mendez Elementary – prompting concerns among parents and caregivers. While the risk to the general public remains low, particularly for those vaccinated, the recent cases serve as a crucial reminder of the importance of preventative measures against this contagious viral infection. Understanding how mumps spreads and taking appropriate steps to protect yourself and your family is paramount, especially as vaccination rates have seen a decline in recent years.
The recent alerts began with a notification from Berkeley High School regarding a possible exposure on February 2, 2026. Parents and staff were informed that individuals present at the school on that date may have been exposed. A subsequent investigation revealed a similar situation at Sylvia Mendez Elementary, with potential exposures occurring on January 14 and 15, 2026. However, health officials emphasize that the current cases appear to be contained within a single household unit with incomplete vaccination status, and there is currently no evidence of widespread community transmission within the City of Berkeley.
Understanding Mumps and How It Spreads
Mumps is a viral infection that primarily affects the salivary glands, causing them to swell and become tender. Symptoms typically begin with fever, headache, muscle aches, tiredness, and loss of appetite, followed by the characteristic swelling of the salivary glands. The virus spreads through droplets of saliva and mucus when an infected person coughs, sneezes, or talks. Close contact, such as sharing utensils or cups, can also facilitate transmission. According to the Centers for Disease Control and Prevention (CDC), there were 348 reported cases of mumps across the United States in 2025 [1].
Who is at Risk?
Individuals who have not been vaccinated against mumps or who have not received two doses of the measles, mumps, and rubella (MMR) vaccine are at the highest risk of infection. The effectiveness of the MMR vaccine is well-established, with two doses providing approximately 88% protection against mumps [CDC Mumps Information]. However, even vaccinated individuals can sometimes contract mumps, although symptoms are typically milder. The recent decline in vaccination rates, coupled with increasing exemptions, is contributing to a heightened risk of outbreaks.
Protecting Yourself and Your Family
The most effective way to protect against mumps is vaccination. The CDC recommends that children receive two doses of the MMR vaccine, with the first dose administered between 12 and 15 months of age and the second dose between 4 and 6 years of age. Adults born in 1957 or later who have not been vaccinated or do not have evidence of immunity should also receive two doses of the MMR vaccine. Beyond vaccination, practicing good hygiene can help prevent the spread of the virus. This includes frequent handwashing with soap and water, covering your mouth and nose when coughing or sneezing, and avoiding close contact with individuals who are sick.
If you or your child are susceptible and believe you may have been exposed to mumps, it’s crucial to monitor for symptoms. Symptoms may develop between February 14, 2026, and February 27, 2026, for those exposed at Berkeley High School. The exposure window for Sylvia Mendez Elementary has closed, according to officials [2]. If symptoms develop, contact your healthcare provider immediately. Early diagnosis and supportive care can help manage the infection and prevent complications.
The Importance of Vaccination Rates
The current situation in Berkeley highlights a broader national trend of declining vaccination rates and increasing exemptions. This trend is concerning, as it increases the risk of outbreaks of vaccine-preventable diseases like mumps, measles, and rubella. Dr. Peter Chin-Hong, Professor of medicine at UCSF, emphasized that the risk to the general public is “very, very low if you’ve been vaccinated” [1]. Maintaining high vaccination coverage is essential for protecting both individuals and the community through herd immunity.
As health officials continue to investigate the recent cases in Berkeley, it’s important for residents to remain vigilant and take proactive steps to protect themselves and their families. Staying informed about mumps, understanding the importance of vaccination, and practicing good hygiene are key to preventing the spread of this contagious virus. The City of Berkeley Public Health Department is continuing to monitor the situation and will provide updates as needed.
This information is for general knowledge and informational purposes only, and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
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