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Measles - Q&A about Disease & Vaccine

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General Questions

What is measles?
Measles is an infectious viral disease that occurs most often in the late winter and spring. It begins with a fever that lasts for a couple of days, followed by a cough, runny nose, and conjunctivitis (pink eye). A rash starts on the face and upper neck, spreads down the back and trunk, then extends to the arms and hands, as well as the legs and feet. After about 5 days, the rash fades in the same order in which it appeared.

How can I catch measles?
Measles is highly contagious. An infected person can spread measles to others even before he or she develops symptoms—from four days before they develop the measles rash through four days afterward. The measles virus lives in the mucus in the nose and throat of infected people. When they sneeze or cough, droplets spray into the air. These droplets can infect others for up to 2 hours after the person with measles leaves the room.

How serious is the disease?
Measles can cause serious health complications, such as pneumonia or encephalitis, and even death. Children younger than 5 years of age and adults older than 20 years of age are at high risk of getting a serious case of measles. About 1 in 4 unvaccinated people in the U.S. who get measles will be hospitalized; 1 out of every 1,000 people with measles will develop brain swelling (encephalitis); 1 or 2 out of 1,000 people with measles will die, even with the best care.

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Why is vaccination necessary?
Before the U.S. measles vaccination program started in 1963, about 3-4 million people in the U.S. got measles each year; 400-500 of them died, 48,000 were hospitalized, and 4,000 suffered encephalitis (brain swelling) due to measles. Widespread use of measles vaccine has led to a greater than 99% reduction in measles cases in the United States compared with the pre-vaccine era.

However, measles is still common in other countries, and measles cases continue to be brought into the United States by unvaccinated travelers (Americans or foreign visitors) who get measles while they are in other countries. Measles is highly contagious, so anyone who is not protected against measles is at risk of getting the disease. People who are unvaccinated for any reason, including those who refuse vaccination, risk getting infected with measles and spreading it to others, including those who cannot get vaccinated because they are too young or have specific health conditions. If vaccinations were stopped, measles cases would return to pre-vaccine levels and hundreds of people would die in the U.S. from measles-related illnesses.

Is measles still a problem in the United States?
Yes. Every year, measles is brought into the United States by unvaccinated travelers (Americans or foreign visitors) who get measles while they are in other countries. They can spread measles to other people who are not protected against measles, which sometimes leads to outbreaks. This can occur in communities with unvaccinated people.

Most people in the United States are protected against measles through vaccination, so measles cases in the U.S. are uncommon compared to the number of cases before a vaccine was available. Measles was eliminated from the U.S. in 2000 (elimination is defined as the interruption of continuous measles transmission lasting more than 12 months). Since elimination was declared in 2000, the annual number of people reported to have measles ranged from a low of 37 people in 2004 to a high of 668 people in 2014.

However, in 2008, 2011, 2013 and 2014, there were more reported measles cases compared with previous years. CDC experts attribute this to outbreaks of measles occurring in countries to which Americans often travel because each year unvaccinated travelers get measles while abroad, then bring the virus back to the U.S. There was also more spread of the measles virus in recent years since individuals who opt out of vaccine tend to cluster in groups.  These groups of susceptible individuals then accumulate and age over time.  This makes them susceptible to outbreaks when someone brings the virus into the group from abroad. 

If measles is eliminated from the U.S., why do I need the vaccine?
Vaccination has enabled us to reduce measles and most other vaccine-preventable diseases to very low levels in the United States. However, measles is still very common—even epidemic—in other parts of the world. Visitors to our country and unvaccinated U.S. travelers returning from other countries can unknowingly bring (import) measles into the United States. Since the virus is highly contagious, such imported cases can quickly spread, causing outbreaks or epidemics among unvaccinated people and under-vaccinated communities.

To protect your children, yourself, and others in the community, it is important to be vaccinated against measles. You may think your chance of getting measles is small, but the disease still exists, and anyone who is not protected is at risk of getting the disease in the United States and while traveling internationally.

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What kind of vaccine is given to prevent measles?
The measles-mumps-rubella (MMR) vaccine provides long-lasting protection against all strains of measles, as well as 2 other viral diseases—mumps and rubella. These 3 vaccines are safe given together. MMR is an attenuated (weakened) live virus vaccine. This means that after injection, the viruses grow and cause a harmless infection in the vaccinated person with very few, if any, symptoms. The person's immune system fights the infection caused by these weakened viruses and immunity develops.

How effective is MMR vaccine?
The measles vaccine is very effective. One dose of measles vaccine is about 93% effective at preventing measles if exposed to the virus and two doses are about 97% effective.

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Why is MMR vaccine given after the first birthday?
Most infants born in the United States will receive passive protection against measles, mumps, and rubella in the form of antibodies from their mothers. These antibodies can destroy the vaccine virus if they are present when the vaccine is given and, thus, can cause the vaccine to be ineffective. By 12 months of age, almost all infants have lost this passive protection.

What is the best age to give the second dose of MMR vaccine?
Children should receive two doses of MMR vaccine–the first dose at 12 through 15 months of age and the second dose at 4 through 6 years of age. Giving the second dose of the vaccine earlier is allowed at any time as long as it is at least 28 days after the first dose.

As an adult, do I need the MMR vaccine?
Most adults need one dose of MMR vaccine unless they have evidence of measles immunity. However, adults who are at a high risk of measles exposure, including students in post-high school institutions, healthcare personnel, and international travelers, need two doses of MMR vaccine unless they have evidence of immunity.

Acceptable evidence of immunity against measles includes at least one of the following:

  • written documentation of past vaccination:
    • with one or more doses of measles-containing vaccine administered on or after the first birthday for adults not at high risk
    • with two doses of measles-containing vaccine for adults at high risk, including college students in post-high school institutions, healthcare personnel, and international travelers
  • blood tests that show they are immune to measles, mumps, and rubella
  • laboratory confirmation that they had measles, mumps, and rubella
  • birth before 1957 (and are presumed immune by age)
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Do people who received measles vaccine in the 1960s need to have their dose repeated?
Not necessarily. People who have documentation of receiving LIVE measles vaccine in the 1960s do not need to be revaccinated. People who were vaccinated prior to 1968 with either inactivated (killed) measles vaccine or measles vaccine of unknown type should be revaccinated with at least one dose of live attenuated measles vaccine. This recommendation is intended to protect those who may have received killed measles vaccine, which was available in 1963-1967 and was not effective.

Why are people born before 1957 exempt from receiving MMR vaccine?
People born before 1957 lived through several years of epidemic measles before the first measles vaccine was licensed. As a result, these people are very likely to have had the measles disease. Surveys suggest that 95% to 98% of those born before 1957 are immune to measles. Note: The "1957 rule" does not apply to women of childbearing age who could become pregnant. (Because rubella can occur in some people born before 1957 and because congenital rubella and congenital rubella syndrome can occur in the offspring of women infected with rubella virus during pregnancy, birth before 1957 is not acceptable evidence of rubella immunity for women who could become pregnant.)

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Precautions and Possible Reactions

I am 2 months pregnant. Is it safe for me to have my 15-month-old child vaccinated with the MMR vaccine?
Yes. Measles, mumps, and rubella vaccine viruses are not transmitted from the vaccinated person, so MMR does not pose a risk to a pregnant household member.

I am breast feeding my 2-month-old baby. Is it safe for me to receive the MMR vaccine?
Yes. Breast feeding does not interfere with the response to MMR vaccine, and your baby will not be affected by the vaccine through your breast milk.

My 15-month-old child was exposed to chickenpox yesterday. Is it safe for him to receive the MMR vaccine today?
Yes. Disease exposure, including chickenpox, should not delay anyone from receiving the benefits of the MMR or any other vaccine.

What are the most common side effects following MMR vaccine?
Most people have no side effects from the MMR vaccine. The side effects that do occur are usually very mild, such as a fever or rash. More serious side effects are rare. These may include high fever that could cause a seizure (in about 1 person out of every 3,000) and temporary pain and stiffness in joints (mostly in teenage and adult women who weren't already immune to rubella).

Who should not receive MMR vaccine?
Some people should not get MMR vaccine or should wait.

  • Anyone who has ever had a life-threatening allergic reaction to the antibiotic neomycin, or any other component of MMR vaccine, should not get the vaccine. Tell your doctor if you have any severe allergies.
  • Anyone who had a life-threatening allergic reaction to a previous dose of MMR or measles-mumps-rubella-varicella (MMRV) vaccine should not get another dose.
  • Some people who are sick at the time the shot is scheduled may be advised to wait until they recover before getting MMR vaccine.
  • Pregnant women should not get MMR vaccine. Pregnant women who need the vaccine should wait until after giving birth. Women should avoid getting pregnant for 4 weeks after vaccination with MMR vaccine.
  • Tell your doctor if the person getting the vaccine:
    • Has HIV/AIDS, or another disease that affects the immune system
    • Is being treated with drugs that affect the immune system, such as steroids
    • Has any kind of cancer
    • Is being treated for cancer with radiation or drugs
    • Has ever had a low platelet count (a blood disorder)
    • Has gotten another vaccine within the past 4 weeks
    • Has recently had a transfusion or received other blood products

Any of these might be a reason to not get the vaccine, or delay vaccination until later.

MMR and Autism Theory

Vaccines Do Not Cause Autism

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