Mumps Outbreak at San Diego State University: What You Should Know About Risks, Symptoms and Prevention

Written By Julia Ramirez

A recent mumps outbreak at San Diego State University has brought renewed attention to a disease many Americans haven't thought about in decades. Although mumps became relatively uncommon in the United States following widespread vaccination, outbreaks can still occur, particularly in settings where people live, work and socialize in close quarters.

The outbreak, first identified in September 2026, initially involved members of SDSU's football program. By October 6, university officials reported 25 cases, including 18 confirmed and seven probable infections. San Diego County public health officials have been working with the university to identify close contacts, monitor additional cases and provide vaccination clinics.

While the outbreak has primarily affected young adults, mumps can occur at any age. Understanding how the virus spreads, recognizing its symptoms and reviewing your vaccination history are important steps in protecting yourself and your family.

Why Is Mumps Making a Comeback?

Mumps is a contagious viral infection that spreads through saliva and respiratory droplets. Coughing, sneezing, kissing, sharing drinks or spending extended periods in close contact with an infected person can transmit the virus.

College campuses are particularly susceptible to outbreaks because students often share living spaces, dining facilities, athletic equipment and social environments. Athletic teams may face additional exposure through frequent close contact during practices, training and travel.

Another factor is that immunity from childhood vaccination can decrease over time. The measles, mumps and rubella (MMR) vaccine remains highly effective, but it does not provide complete protection against mumps. According to the Centers for Disease Control and Prevention (CDC), two doses are approximately 86% effective at preventing the disease.

This means that even fully vaccinated individuals can occasionally become infected, particularly during outbreaks involving repeated close exposure. However, vaccinated individuals are generally less likely to develop severe symptoms or complications.

What Are the Symptoms of Mumps?

Mumps symptoms typically appear 12 to 25 days after exposure, with most people developing symptoms around 16 to 18 days after infection.

Early symptoms can resemble those of a common viral illness and include:

  • Fever and headache

  • Muscle aches and fatigue

  • Loss of appetite

  • General discomfort or weakness

  • Swelling and tenderness around the cheeks, jaw or salivary glands

The most recognizable symptom is swelling of the salivary glands near the ears, which can cause puffy cheeks and a painful jaw. This swelling may occur on one or both sides of the face.

Some individuals experience only mild symptoms, while others may have no noticeable symptoms at all. Importantly, an infected person can spread the virus before realizing they are sick.

Who Is Most at Risk?

Although mumps is often associated with childhood, the virus can affect people of all ages.

Children: Routine childhood immunizations have significantly reduced mumps infections. Children who have not received the recommended vaccinations remain at greater risk.

Teenagers and college students: Adolescents and young adults may be more susceptible in close-contact environments such as schools, dormitories, athletic teams and social gatherings.

Adults: Adults who were never vaccinated, received only one dose or have uncertain vaccination histories may be vulnerable. Even adults who completed their childhood vaccinations can occasionally develop mumps as immunity decreases over time.

People with weakened immune systems: Individuals with compromised immune function may have additional health concerns related to infection and should discuss exposure and prevention with their physician.

Complications from mumps are relatively uncommon but tend to occur more frequently in adolescents and adults than in young children. These can include inflammation of the testicles or ovaries, inflammation of the pancreas, hearing loss and, rarely, inflammation involving the brain or its surrounding tissues.

Most people recover completely within approximately two weeks, but recognizing symptoms and seeking appropriate medical guidance is important.

What Precautions Should You Take?

The most effective protection against mumps is vaccination, along with basic precautions that help reduce the spread of respiratory infections.

Review your vaccination history. The CDC recommends two doses of MMR vaccine for children, with the first dose generally given between 12 and 15 months and the second between ages 4 and 6. College students, international travelers and healthcare personnel should generally have documentation of two doses or other acceptable evidence of immunity.

Ask whether an additional dose is appropriate. During an outbreak, public health officials may recommend a third MMR dose for people identified as being at increased risk. This is not a routine recommendation for every adult.

Avoid sharing drinks and personal items. Mumps spreads through saliva, making shared beverages, eating utensils and other items that come into contact with the mouth potential sources of transmission.

Practice good respiratory hygiene. Regular handwashing, covering coughs and sneezes, and limiting close contact with people who are sick can help reduce transmission.

Stay home if symptoms develop. People with suspected mumps should contact their healthcare provider and avoid close contact with others. The CDC recommends isolation for five days after salivary gland swelling begins.

Monitor symptoms following exposure. Anyone who has been in close contact with a person diagnosed with mumps should watch for symptoms for 25 days after their last exposure, even if fully vaccinated.

If you suspect you have mumps, call your healthcare provider before arriving at the office so appropriate precautions and testing arrangements can be made.

Should Adults Consider a Mumps Booster?

For most adults who have completed the recommended vaccination series and have no known exposure or increased risk, an additional MMR dose is not routinely necessary.

However, individuals who are unsure of their vaccination history, have received only one dose or have been identified as part of a higher-risk group during an outbreak should speak with their physician.

It is also important to understand that receiving an MMR vaccination after exposure does not reliably prevent an infection that has already occurred. Vaccination can, however, help protect against future exposure.

A Reminder About Preventive Care

The recent SDSU outbreak is a reminder that vaccine-preventable illnesses have not disappeared entirely. While mumps remains relatively uncommon in the United States, cases can arise when people spend extended periods in close contact, particularly when immunity has decreased over time.

At Williams + Weiss Executive Medicine, we encourage patients to stay informed about their immunization history and discuss any concerns about exposure, vaccination or symptoms with their physician. Reviewing preventive healthcare needs is an important part of maintaining good health at every age.

If you have questions about your vaccination status or believe you may have been exposed to mumps, please contact our office for guidance.

Sources and references

The article is based on the following reporting and public health guidance:

Julia Ramirez
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