Measles
As of February 2, 2026, the overall measles risk in Marin County remains LOW, with no confirmed local cases. California has reported 9 measles cases to date, compared to 25 cases total last year. While no cases have been identified in Marin, measles activity has been reported elsewhere in the state, including Southern California and the Bay Area, increasing the risk of exposure for people who are unvaccinated or under-vaccinated. Marin County Public Health continues to monitor the situation and encourages residents to stay up to date on recommended measles vaccinations, especially before travel.
Current Marin County Public Health Recommendation: Measles Vaccination
Due to ongoing measles outbreaks nationwide, Marin County Public Health recommends that infants aged 6 to 11 months receive an early MMR dose before traveling to any area in the United States with an increased measles risk. All international travelers ages 6 months and older should be vaccinated against measles before traveling. Measles cases often start when unvaccinated or under-vaccinated people travel and then spread the disease to others who are not protected. Travelers should be especially careful before visiting Mexico, where there is an ongoing measles outbreak with nearly 8,000 reported cases.
Reference: Rader B, Walensky RP, Rogers WS, Brownstein JS. Revising US MMR Vaccine Recommendations Amid Changing Domestic Risks. JAMA. Published online March 14, 2025.
Read the Public Health Advisory issued March 11, 2025.
Reviewed and updated February 3, 2026.
What is Measles?
Measles is a childhood disease caused by a virus. It was once widespread, but now it can almost always be prevented with a vaccine. Also known as rubeola, measles spreads quickly through the air and can be very serious or even deadly for small children. Although more kids are getting vaccinated and death rates are decreasing worldwide, measles still kills over 200,000 people each year, primarily children. Due to high vaccination rates, measles hasn’t been widespread in the United States for about 20 years. Most recent measles cases in the U.S. came from outside the country and happened to people who were unvaccinated or didn’t know if they had been vaccinated. Here is a succinct history of measles.
Why are there Measles Outbreaks in the United States?
Measles outbreaks in the United States are happening for a few reasons:
- Lower Vaccination Rates: Some people are not getting vaccinated or are unsure of their vaccination status. This is partly due to misinformation about vaccines.
- Travel: Travelers from areas where the disease is more prevalent can introduce measles into the country. Vaccine rates are often lower in these countries, sometimes because of limited access to healthcare.
- Highly Contagious: Measles spreads quickly through the air and can linger in a room for up to two hours after an infected person leaves.
These factors, combined, have led to recent outbreaks, especially in areas with lower vaccination rates.
Can a Measles Outbreak Happen in Marin County?
Yes, a measles outbreak can happen in Marin County. In 2015, Marin County had its first confirmed cases when two unvaccinated siblings contracted the disease. California has experienced several measles outbreaks in recent years. In 2019, California had 73 confirmed cases, with 41 linked to six different outbreaks. The largest outbreak involved 21 cases at a healthcare facility, illustrating the rapid spread of the measles virus.
In Marin County, most children entering school are vaccinated, with rates around 99%. This helps protect the community from diseases like measles. However, with measles cases on the rise across the country, it's essential to remain vigilant, keep vaccinations up to date, and stay informed.
Why is there a Large Measles Outbreak in the United States?
As of December 23, 2025, the United States has reported 2,012 confirmed measles cases, including 1,988 cases across 44 jurisdictions and 24 cases among international visitors. In 2025, 50 outbreaks have been reported, accounting for 87% of all confirmed cases, compared with 16 outbreaks in 2024.To date, there have been three (3) deaths due to measles. In 2025, measles outbreaks in the United States have occurred predominantly in undervaccinated communities, where lower measles-mumps-rubella (MMR) vaccination coverage has facilitated sustained transmission following introductions of the virus. A vaccination rate of 95% is needed to protect against measles outbreaks.
About Measles
Rash
Signs and Symptoms
Measles symptoms typically appear 7 to 14 days after exposure to the virus. Common measles symptoms include:
- High Fever (may spike to more than 104° F)
- Cough
- Runny Nose (Coryza)
- Red, Watery Eyes (Conjunctivitis)
- A red rash (characterized by a combination of flat, discolored patches and raised bumps) begins on the face and head a few days after the onset of respiratory symptoms and persists for 5-6 days.
Complications
Measles can cause serious health complications, especially in children younger than 5 years of age. Common complications are ear infections and diarrhea. Serious complications include pneumonia and encephalitis, often resulting in hospitalizations. Measles illness during pregnancy increases the risk of premature labor, low-birthweight children, and spontaneous abortion.
Treatment
There is no specific treatment for measles once it occurs. Treatment focuses on relieving symptoms and preventing complications. Medications like fever reducers (acetaminophen, ibuprofen, or naproxen) can help manage symptoms. Antibiotics may be prescribed if a bacterial infection, like pneumonia, occurs. Please be aware of this when giving aspirin to children because of the risk of Reye's syndrome. Under the direction of a healthcare provider, vitamin A administration may be appropriate. Vitamin A has been shown to reduce complications and the risk of death in severe measles cases in children in developing countries, where vitamin deficiencies are common due to inadequate nutrition.
Protection After Exposure (also called Post Exposure Prophylaxis or PEP)
People without immunity can get protection after exposure. To reduce symptoms, they may receive a measles vaccine within 72 hours or immune serum globulin injections within six days of exposure. The MMR vaccine and IG cannot be administered simultaneously. Contact your healthcare provider if you think you have been exposed to a person who has been sick with measles.
Measles Vaccine
Marin County Public Health does not recommend that children aged 6 months to 12 months receive an earlier dose of the measles vaccine unless they are traveling to a region with high measles activity.
The MMR vaccine protects you and your child against three serious viral infections: measles, mumps, and rubella. These infections are highly contagious among people who aren’t vaccinated and cause severe health complications. Children should receive two doses of the MMR vaccine, starting with the first dose at 12 to 15 months of age and the second dose at 4 to 6 years of age. Teens and adults should also be up to date on their MMR vaccination. Children may also get the MMRV vaccine, which protects against measles, mumps, rubella, and varicella (chickenpox). This vaccine is only licensed for use in children aged 12 months through 12 years.
Is MMR a Live Vaccine?
Measles, Mumps, and Rubella vaccines are not recommended during pregnancy or for anyone with a weakened immune system.
The MMR vaccine is a weakened (attenuated) live virus. That means after you receive it, the viruses cause a harmless infection with few or no symptoms. Then, your body eliminates the viruses. Your immune system fights the disease caused by weakened viruses, and your immunity to these viruses develops.
Is the MMR Vaccine Safe?
The MMR vaccine has some side effects. Reactions can include a sore arm, fever, mild rash, swollen glands, and joint pain. Rare severe reactions include seizures or a low platelet count. Adverse reactions should be reported to the Vaccine Adverse Event Reporting System (VAERS). You can learn more at the VAERS website.
Why Haven't Vaccines Eliminated Measles?
In 1974, the World Health Organization (WHO) initiated a global immunization program aimed at reducing illnesses and deaths from vaccine-preventable diseases. Efforts to eliminate measles in the Americas began in 1991 by giving an extra dose of the vaccine to those aged 9-15. In 1998, a false study claimed a link between the MMR vaccine and autism, causing a significant drop in vaccination rates. By 2012, Marin County's kindergarten vaccination rate had dropped to its lowest point, 77.9 percent, earning the county a nationwide reputation for being anti-vaccine. Because measles spreads quickly, maintaining at least 95% immunity is crucial to preventing outbreaks.
Can Vitamin A Prevent Measles?
No. Vitamin A cannot prevent measles, but it can help reduce the severity of the disease. Measles does not have a specific antiviral treatment, but supportive care, including vitamin A administration under the direction of a healthcare provider, may be appropriate. Vitamin A has been shown to reduce complications and the risk of death in severe measles cases in children in developing countries, where vitamin deficiencies are common due to inadequate nutrition. However, it is not a substitute for vaccination, which remains the most effective way to prevent measles.
Healthcare Provider Information
Testing
Measles testing can be performed at many commercial laboratories. Please call Marin County Public Health at 415-473-4163 if you need assistance with measles testing.
Reporting
According to Title 17 of the California Code of Regulations, measles is a reportable disease to the Public Health. If you are a healthcare provider and have a patient who is suspected or confirmed to have measles, please report it to Marin County Public Health immediately (415-473-4163).