Measles - updated January 29, 2024

Montgomery County Department of Health and Human Services (HHS) Office of Public Health (MCOPH) Update on Measles Outbreak - January 22, 2024

Montgomery County Health Officials are tracking local potential and confirmed exposures related to a measles outbreak in Philadelphia. Currently, there are nine confirmed cases in Philadelphia and no confirmed cases in Montgomery County. This page will no longer be updated until there is a new confirmed exposure or case in Montgomery County. MCOPH will continue to conduct active (enhanced) surveillance for measles until the outbreak is over. Measles outbreaks are considered over after two incubation periods with no new cases. The incubation period for measles is 21 days. After 42 days with no new associated cases, the MCOPH will declare the outbreak to be ended.

Measles is a highly contagious virus that can lead to serious complications. It spreads easily when an infected person breathes, coughs, or sneezes.  

About 90% of people who have close contact with an infected person will get measles if they are not immune.  

Get a free MMR vaccine for yourself or your child.

Montgomery County residents, who are uninsured or underinsured OR have not previously received an MMR vaccine and have been exposed to an individual with a confirmed case of measles, can call the Montgomery County Office of Public Health Clinics in Norristown at 610.278.5145 or in Pottstown at 610.970.5040 to get an MMR vaccine at no cost regardless of their health insurance status.

Contact Us 

Monday - Friday 
8:00 am - 4:30 pm 

Phone: 610-278-5117

After Hours: 610-635-4300 

Email: (Reviewed Monday-Friday 8:00 am - 4:30 pm)

  1. Transmission
  2. Quarantine & Isolation
  3. Symptoms
  4. Vaccination & Immunity

The measles virus lives in an infected person’s nose and throat mucus. When that person sneezes or coughs, the measles virus sprays into the air and people can breathe in the virus. The virus remains active and contagious in the air for up to 2 hours.  

Infected people can spread the virus to others from four days before and until four days after the rash appears.  


Frequently Asked Questions

How do I know I have been exposed?

Sharing the same airspace with a person infected with measles (same classroom, home, waiting room, airplane, etc.), or being in these areas up to 2 hours after the infectious person has left the area is a measles exposure. Exposure criteria apply even if the infectious person was masked.  

Do I need a booster vaccine?

No. CDC considers people who have received two doses of measles vaccine as children protected for life, and they do not ever need a booster dose.  

How effective is the measles vaccine?

The measles vaccine is very effective. Two doses of the measles vaccine are about 97% effective at preventing measles if exposed to the virus. One dose is about 93% effective.  

I think I have measles. What should I do? 

Call your healthcare provider and let them know about your symptoms so that they can tell you what to do next. If you are going to a healthcare facility for treatment, call the facility first to let them know you are coming so that they can be prepared to take care of you without putting other patients at risk.  

What is the treatment for measles?

There is no specific treatment for measles, but there are medications that can treat some of the symptoms.  

Find More Information 

Measles Overview (Centers for Disease Control)
Stay Alert for Measles Cases (Centers for Disease Control)
Montco Health Officials Warn Residents of Possible Measles Exposures - 1/11/24