Press Enter to show all options, press Tab go to next option

Frequently Asked Questions (FAQs)

measles-infographic 1
measles-infographic 2
measles-infographic 3
student-travel-infographic 1

 Click here to view our main Measles Page


Am I protected against measles?

You are considered protected from measles if you have written documentation (records) showing:

  • You received two doses of measles-containing vaccine.
  • A blood test confirmed that you had measles at some point in your life.
  • A blood test confirmed that you are immune to measles.
  • You were born before 1957.
What should I do if I’m unsure whether I’m immune to measles?

If you’re unsure whether you’re immune to measles, you should first try to find your vaccination records. If you do not have written documentation of your vaccination records, contact your Healthcare Provider to obtain your vaccination records. If you are not vaccinated against measles, you should get vaccinated with measles-mumps-rubella (MMR) vaccine.

Another option is to have a doctor test your blood to determine whether you’re immune. But this option is likely to cost more and will take two doctor’s visits. There is no harm in getting another dose of MMR vaccine if you may already be immune to measles (or mumps or rubella).

Do I ever need a booster vaccine?

Not if you have received two doses of measles vaccine. CDC considers people who received two doses of measles vaccine as children according to the U.S. vaccination schedule protected for life, and they do not ever need a booster dose

If you’re not sure whether you are fully vaccinated, talk with your doctor.

I only received one dose of measles vaccine, am I protected?
One dose of measles vaccine is about 93% effective. Adults with one dose are generally considered protected but, if concerned, persons who only received one dose of measles vaccine can discuss with their healthcare provider whether a second does might be desirable, based upon personal and community risk. 


Where can I get the measles vaccine?
  • Your healthcare provider.
  • Some Urgent Care Walk-In Clinics may carry vaccines. Call to confirm.
  • For individuals who do not have medical insurance, contact our Immunizations Information Line: (530) 666-8552

For more information on vaccines, visit our immunzation page.

How effective is the measles vaccine?
The measles vaccine is very effective. Two doses of measles vaccine are about 97% effective at preventing measles if exposed to the virus. One dose is about 93% effective.
How long does it take for measles vaccine to work in your body?
For the measles vaccine to work, the body needs time to produce protective antibodies in response to the vaccine. Detectable antibodies generally appear within just a few days after vaccination. People are usually fully protected after about 2 or 3 weeks. If you’re traveling internationally, make sure to get up to date on all your MMR shots. You should plan to be fully vaccinated at least 2 weeks before you depart.  If your trip is less than 2 weeks away and you’re not protected against measles, you should still get a dose of MMR vaccine.
How does the measles vaccine work?
When you get measles vaccine, your immune system makes protective virus-fighting antibodies against the harmless vaccine virus. Measles vaccine protects you from wild-type measles because if you have been vaccinated and then are exposed to someone with measles, your body remembers how to fight off the wild-type virus. That’s because the vaccine trained your immune system.
Could I still get measles if I am fully vaccinated?
Very few people—about three out of 100—who get two doses of measles vaccine will still get measles if exposed to the virus. Experts aren’t sure why. It could be that their immune systems didn’t respond as well as they should have to the vaccine. But the good news is, persons who received 2 doses of measles vaccine (fully vaccinated) who still get measles typically have a milder illness. Fully vaccinated people are less likely to spread the disease to other people, including people who can’t get vaccinated because they are too young or have weakened immune systems.


I’ve been exposed to someone who has measles. What should I do?

If you know you have been exposed to someone with measles,contact your healthcare provider right away and let them know that you have been exposed to someone who has measles. Your healthcare provider can:

  • Determine if you are immune to measles based on your vaccination record, age, or laboratory evidence, and
  • Make special arrangements to evaluate you, if needed, without putting other patients and medical office staff at risk.

If you are not immune to measles, MMR vaccine or, for persons at high risk for measles complications, a medicine called immune globulin may help reduce your risk of developing measles. Your doctor can help to advise you and monitor you for signs and symptoms of measles.

If you do not get MMR or immune globulin, you should stay away from settings where there are susceptible people (such as schools, hospitals, or childcare facilities) until your doctor says it’s okay to return. This will help ensure that you do not spread measles to others.

I think I have measles, what should I do?
Immediately call your healthcare provider and let them know about your symptoms so that they can tell you what to do next. Your healthcare provider can make special arrangements to evaluate you, if needed, without putting other patients and medical office staff at risk.
I don’t know if I was exposed, but I am concerned that I may have been, what should I do?
If you are feeling well and you don’t have any known exposure to a confirmed case and were not in any place listed at the date and time of possible exposure, you can check your vaccination records by requesting your records from CAIR the immunization registry. If you are unable to verify vaccination through CAIR, you can contact your healthcare provider to help you determine your immune status. There is no way to determine if someone has measles before they have symptoms, so if you are feeling well, and you don’t have a known exposure, there is no need to seek healthcare. Concerned persons without a known exposure can monitor themselves for fever and other signs and symptoms of measles.