Utah measles outbreak response
Exposure locations
Information about measles in Utah
As cases are reported, public health officials in Utah investigate to identify individuals who are at risk of infection and any locations where possible exposures may have occurred. These exposure locations can be found in the table above.
Measles symptoms typically appear 7 to 14 days after exposure. People who have a high fever (101°F (38.3°C) or higher) and a cough, runny nose, or red eyes may have early stages of measles. A rash will usually appear after 4 days of fever. If you do develop symptoms you should stay away from other people and call your healthcare provider. Call first before you go to a clinic or hospital to prevent other people from exposure.
Information about measles in states surrounding Utah
Measles overview
Symptoms
- High fever: Typically 101°F (38.3°C) or higher with:
- Cough
- Runny nose
- Red, watery eyes
- Rash (Measles rash usually begins as flat red spots on the face at the hairline. The spots then spread down to the neck, belly, arms, legs, and feet.)
Complications
- Pneumonia (a serious lung infection)
- Hospitalization
- Encephalitis or brain swelling (can cause cognitive disability, deafness, and seizures)
- Complications during pregnancy, such as the risk of premature labor (having your baby early), miscarriage, and your baby having a low birth weight
- Seizures
- Weakened immune system that can last weeks to years (increases the risk of bacterial infection and infection from other diseases)
- Death
When symptoms usually start (onset)
The first symptoms of measles start between 1 and 3 weeks after you are infected with the virus. Most people have symptoms at about 2 weeks.
How long it lasts (duration)
The first symptoms (fever, cough, runny nose, watery eyes) last for about 2 to 4 days but can be as short as 1 day or as long as 8 days.
The rash normally lasts 5 to 7 days and begins about 3 to 5 days after the first symptoms start.
Causes
Measles virus
How to prevent measles
- 2 doses of the MMR vaccine (measles, mumps, rubella), or
- 2 doses of the MMRV vaccine (measles, mumps, rubella, varicella)
Treatment
There's no specific treatment for a measles infection once it occurs. Treatment includes providing comfort measures to relieve symptoms, such as rest, and treating or preventing complications.
What are the vaccination rates in Utah?
Most states look at how many kindergarten students have an exemption for the measles vaccine to measure measles vaccination rates.
During the 2024/2025 school year:
- About 10% of in-person kindergarten students in Utah had an exemption for the MMR vaccine or were missing documentation to show they were vaccinated against measles.
- 9.0% of in-person kindergarten students in Utah had an exemption to any school-required vaccine.
- 10.1% of all students in Utah had an exemption to any school-required vaccine, including students in online schools.
You can look up the immunization coverage rates for children in Utah on the Utah Statistics page of the immunization program website. The immunization dashboard school vaccine exemption tab contains statewide and school-specific immunization data. You can also find reports that show trends in school vaccine exemptions for the past 10 years.
Information about breakthrough infections in Utah
What is a breakthrough measles infection?
A breakthrough measles infection happens when someone is vaccinated (they have had at least 1 MMR vaccine) and still gets measles after being exposed to the virus.
Why are some vaccinated people getting measles?
While the measles vaccine is very good at protecting people, it is not perfect. Most people who get the vaccine (97%) are well protected, but about 3% can get sick if they are exposed to the measles virus. During an outbreak, breakthrough infections are expected because high levels of the measles virus are circulating in the community. Two doses of the MMR vaccine are highly effective (97%) at preventing measles. Even a single dose is very effective (93%). It is rare to get a breakthrough infection if you’ve had 2 doses of the MMR vaccine.
If a vaccinated person gets measles, there are still benefits from the vaccine. Vaccinated people are less likely to have severe illness or have severe measles complications. They are also less likely to spread the virus to others.
Why have there been breakthrough infections in Utah?
Even though the MMR vaccine is very effective, it is not 100% effective. This means we can still expect a small percentage of vaccinated people to get sick with measles after being exposed. For example, if 100 vaccinated people are exposed to measles, we can expect about 3 of them to get sick with measles (a breakthrough infection). If 200 vaccinated people are exposed, we can expect about 6 of them to get sick, and so on. This means that with an increasing number of vaccinated people being exposed, we end up with an increasing number of breakthrough infections.
Most people (more than 90%) in Utah have been vaccinated against measles. We believe many hundreds of vaccinated people in Utah have been exposed to measles during the current widespread outbreak. Even though hundreds of vaccinated people have likely been exposed, the vast majority of them have been protected by the vaccine and we only see the few where their body was not able to fight the virus off.
At the same time, a small proportion of Utahns have not been vaccinated. Those people are also being exposed to the virus. Unlike the vaccinated Utahns, a majority of the unvaccinated Utahns who are exposed to the virus will get sick with measles. This is why most of the people getting measles in Utah are unvaccinated even though they make up a small minority of our population.
Why do breakthrough infections happen?
Experts aren’t exactly sure why breakthrough infections happen. It could be that someone’s immune system did not fully respond to the vaccine. Breakthrough infections can also happen in people who have medical conditions or take medications that weaken their body so it cannot fight off the infection even when they have been vaccinated.
Breakthrough infections are more likely to happen in people who have only had 1 dose of the MMR vaccine.
Is a breakthrough infection more mild?
Typically, people who get breakthrough measles usually have mild illness (lower fever, lighter rash, and fewer complications) and are less likely to spread the disease.
Can you be near someone with measles if you've had the measles vaccine?
Most people with 2 doses of the MMR vaccine are well protected, however the risk is not zero.
- It’s rare, but sometimes people who are fully vaccinated (have had 2 doses of the MMR vaccine) can still get infected if they are exposed. This means you should avoid contact with people who have measles (if possible).
- Breakthrough infections are more common when someone lives in a household, or has prolonged close contact, with someone who has measles.
- Adults with only 1 dose of MMR are still at risk for a mild case of measles.
Should you still watch for symptoms if you are vaccinated but have been exposed to measles?
Yes, it is still reasonable to watch for symptoms. While it is quite rare, it is possible for vaccinated people to get measles. If you have been exposed and experience measles-like symptoms, contact your local health department or a healthcare provider for further assessment and testing.
How does the number of breakthrough infections in this outbreak compare to past outbreaks?
Currently, about 6.97% of confirmed measles cases are breakthrough cases. This is consistent with national data trends.
How can people who are not vaccinated protect themselves from measles?
To avoid the chance of measles infection for unvaccinated individuals we recommend the following:
- Surround yourself with other vaccinated persons, especially in your household, if possible.
- If you’re exposed to someone who has the measles, talk to a doctor about post-exposure vaccination or medication.
- Avoid large gatherings and crowded places in areas with known outbreaks and ongoing transmission.
- Consider getting the MMR vaccine at least 1 month before you try to get pregnant, to avoid harm to your baby during pregnancy.
- Stay away from others if they are sick.
If you think you or your child may have measles, we recommend you:
- Stay home and away from others as much as possible.
- Seek care if you have a hard time breathing and/or fever won’t come down.
- Call the clinic or provider ahead of time and let them know you are concerned about measles; this is to protect other people from getting exposed in the waiting area, such as pregnant women and babies.
More information about measles
- Frequently asked questions about measles (PDF)
- Measles fact sheet (English) (Spanish) (Arabic) (Dari) (Ukrainian)
Measles resources
- Prepare for and respond to measles: Checklist for summer camps (PDF)
- Prepare for and respond to measles: Checklist for K–12 schools (PDF)
- Prepare for and respond to measles: A resource for K–12 schools (PDF)
- Prepare for and respond to measles: Checklist for early care and education centers (PDF)
- Prepare for and respond to measles: Checklist for businesses (PDF)
- Prepare for and respond to measles: A resource for businesses (PDF)
- Prepare for and respond to measles: A resource for shelters and congregate setting facilities