Increased Measles Activity: How to Protect Your Family

What is happening now?

Refer to this page for an up-to-date list of locations of any recent measles exposures.

On June 24, 2026, the Pennsylvania Department of Public Health (DOH) announced a measles outbreak in several counties across Pennsylvania.

The PA DOH is recommending "early" or "catch-up" MMR vaccines for people who live in or visit the following Pennsylvania counties and are not fully vaccinated:

• Berks 
• Chester
• Dauphin  
• Lancaster 
• Lebanon 
• Northumberland 
• York 

The MMR vaccine is also recommended for people who will be traveling internationally and are not fully protected.

Current guidance from the PA DOH is as follows:

• Infant vaccinations: Infants aged 6-11 months can receive one early dose. This early dose protects your baby now, when they need it most, during an outbreak. They will still need to get two doses when they are older. 
• Accelerated vaccinations: Children 12 months or older who haven’t been vaccinated should receive one dose, and then a second dose at least 28 days later. Children who have received one dose should receive a second dose at least 28 days after the first. This “accelerated” second dose will complete their two-dose series early. 
• Catch-up vaccinations: Anyone over 12 months of age who has not received the MMR vaccine should get a two-dose series. The second dose should be at least 28 days after the first dose. Adults born in 1957 or earlier without evidence of immunity should follow the same directions. 
• Fully vaccinated: If you have received two doses of the MMR vaccine, you are considered fully vaccinated and do not need a booster. 
• Special note for children who are immunocompromised: Some children with weak immune systems can’t get MMR because it’s a live vaccine—for example, those on chemotherapy, after a transplant, on immunosuppressing medicines, or those with certain serious immune disorders. If your child has a weak immune system, talk with your child’s care team before getting the MMR vaccine. This is another reason why community vaccination matters: When more people are vaccinated, measles has less chance to spread. This helps protect babies and children who cannot get the vaccine. 

How to get the MMR vaccine at CHOP Primary Care 

If your child is a patient at CHOP Primary Care and needs the MMR vaccine, call your child’s primary care office. Ask for a nurse visit to receive the MMR vaccine.   

Keep reading to learn more about measles, and why early vaccinations are sometimes recommended for children.

What is measles?

Measles is a highly contagious, viral respiratory illness. It spreads through the air when a person with measles breathes, coughs, or sneezes. It is one of the most infectious viruses that we see. 

For example, when a person has norovirus (a highly contagious stomach virus), they typically infect about 2 other people. When a person has measles, they can infect about 12-18 other people who are not immune to measles. 

What are the symptoms of measles? 

Measles can start with cold-like symptoms such as a runny nose/congestion, cough or fever. Additional symptoms include: 

• Red, watery eyes, also known as pink eye (conjunctivitis)
• Small white spots inside the mouth, known as Koplik’s spots, that develop about two to four days before rash onset, but quickly disappear after rash appears
• A distinct blotchy, red rash that usually appears two to four days after the first symptoms (though this can vary) and starts on the face and neck and spreads downward

Why is measles so serious?

Some people with measles may experience complications, such as pneumonia, swelling of the brain, seizures and — in extreme cases — death.

• 1 in 20 children with measles get pneumonia
• 1 in 5 children with measles are sick enough to need hospitalization
• Approximately 1 to 3 out of 1,000 children who get measles die from their infection

Once a common childhood illness that affected mostly preschool- and school-aged children, measles has been relatively nonexistent in the U.S. in recent years. This low incidence of measles is the result of widespread vaccination. Measles vaccination is highly effective in preventing infection. Unfortunately, we are seeing rising cases of measles in the last few years because of decreases in vaccination rates.

There is no cure for measles. There are no antibiotics or antiviral medications that treat measles.

How can I protect my family during measles outbreaks?

The most important thing you can do is make sure all children and adults in your household are up to date on their recommended vaccinations — all of them. 

Because measles is highly contagious, it’s also important for parents to take precautions with children who are either too young to be vaccinated, have weak immune systems, or who cannot get the vaccine for medical reasons. 

During periods of outbreak, non-immune individuals (including infants under 1 year or people with weakened immune systems) should avoid travel and visits to areas of current transmission, as well as exposure to non-immune or any ill individuals (even if it is “just a cold”). 

If you live in or cannot reschedule your visit to an area where multiple cases of measles have recently been reported, it’s important to limit your susceptible child’s exposure to other people and public areas where infected people might have visited. 

During periods when outbreaks are not occurring, it’s safe to run normal errands with your baby — just be sure to practice the usual precautions to keep your child from getting sick:  

• Do not let strangers hold or play closely with your baby. 
• Keep your child away from people who have a fever, cough, or other signs of illness. 
• Wash your hands often. 
• Ask others to wash their hands before touching your baby. 
• Make sure family members are up to date on their vaccines. 

What should you do if you think you have been exposed to or infected with measles?

Due to the highly contagious nature of measles, please contact your child’s healthcare provider before you go to a doctor’s office, urgent care, emergency department or care center if you believe you have been exposed to or may be infected with measles. They will give advice on precautions to take before entering any facility to avoid potentially exposing others. 

Why is the MMR vaccine sometimes given early during outbreaks, but not always?  

When there’s a measles outbreak in the community, health officials may recommend giving the MMR vaccine earlier than usual to protect babies as soon as possible. That’s because the chance of catching measles is higher during an outbreak, and measles can be especially serious for infants and small children. 

When there isn’t an outbreak, we follow the routine vaccine schedule because it’s designed for the ages when the vaccine works best to provide the most long-lasting protection.  

In younger babies, the vaccine can be a little less effective because some protection passed from a parent (maternal antibodies) can interfere with how well the vaccine “takes.”  

The vaccine is still safe to give early — an early dose just adds protection sooner when risk is high for small children, and routine doses are still needed later.  

If the vaccine is so effective, and 90 percent of U.S. population has been vaccinated, why is measles spreading?

The MMR vaccine is extremely effective — about 95 to 99 of 100 people who have been vaccinated will be protected.

However, measles is extremely contagious. In any place where crowds of people gather, a person with measles could expose many others. The threshold to have herd immunity, which reduces transmission of measles in a population, is >95% vaccination coverage. We have fallen below 95% in the U.S. (and significantly below in some areas/populations), resulting in increasing outbreaks. 

Unfortunately, some of those exposed may not be immune because: 

• They are too young to be immunized. 
• They have a medical reason why they cannot be immunized. 
• They have a weakened immune system and may not be protected by the vaccine. 
• Their parent/guardian chose not to get the measles vaccine for them as a child. 
• They may never have received the vaccination by choice. 
• They are one of the rare few for whom the vaccine didn’t work. 

For these reasons, measles can quickly spread through a population when unvaccinated or susceptible people are exposed. This is why staying up to date on vaccinations is so important: Vaccines break the chain of transmission.  

Is the measles vaccine safe?

Yes. The MMR vaccine is safe for most people. 

Like any medicine, vaccines do have side effects. Most side effects are mild, such as fever or soreness where the shot was given.  

Scientific studies have long confirmed the safety of the MMR vaccine. Concerns about vaccines causing autism have been addressed by dozens of scientific studies and have shown that children who receive vaccines are at no greater risk for developing autism than those who do not receive vaccines. 

On the flip side, children who do not receive vaccines are at a higher risk of getting diseases that vaccines can help prevent.  

Get more information about measles and the MMR vaccine from CHOP’s Vaccine Education Center.

• Watch "Doctors Talk: Measles"
• A Look at the Measles, Mumps and Rubella (MMR) Vaccine
• Measles: What You Should Know (Q&A) in English | Spanish | Japanese
• News & Views: What Should I know About the New MMR Vaccine, PRIORIX?