Frequently Asked Questions about Measles in the U.S.
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- Has measles been eliminated from the United States?
- What does measles elimination mean?
- If measles is eliminated, why do people still get it in the United States?
- Where do cases of measles that are brought into the United States come from?
- Why have there been more measles cases in the United States in recent years?
- How effective is the measles vaccine?
- Could I still get measles if I am fully vaccinated?
- Do I ever need a booster vaccine?
- Am I protected against measles?
- What should I do if I’m unsure whether I’m immune to measles?
- How common was measles in the United States before the vaccine?
- Is measles a concern for the United States?
- Could measles ever re-establish itself in the United States?
- What are the vaccine coverage levels like in the United States?
- Will the United States ever get rid of measles completely?
- What is CDC’s role in responding to measles cases and outbreaks?
- What is wild-type measles virus?
- How is the type of measles virus identified?
A: Yes. In 2000, the United States declared that measles was eliminated from this country. The United States was able to eliminate measles because it has a highly effective measles vaccine, a strong vaccination program that achieves high vaccine coverage in children and a strong public health system for detecting and responding to measles cases and outbreaks.
A: Measles elimination is defined as the absence of continuous disease transmission for 12 months or more in a specific geographic area. Measles is no longer endemic (constantly present) in the United States.
A: 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. Since 2000, when measles was declared eliminated from the U.S., the annual number of people reported to have measles ranged from a low of 37 people in 2004 to a high of 667 people in 2014.
A: Measles can be brought into the United States from any country where the disease still occurs or where outbreaks are occurring including Europe, Africa, Asia, and the Pacific. Worldwide, about 20 million people get measles each year; about 146,000 die. In recent years, many measles cases have been brought into the United States from common U.S. travel destinations, such as England, France, Germany, India, and, during 2014, from the Philippines and Vietnam.
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Q: Why have there been more measles cases in the United States in recent years?
A: In 2008, 2011, 2013 and 2014, there were more reported measles cases compared with previous years. CDC experts attribute this to:
- more measles cases than usual in some countries to which Americans often travel (such as England, France, Germany, India, the Philippines and Vietnam), and therefore more measles cases coming into the US, and/or
- more spreading of measles in U.S. communities with pockets of unvaccinated people.
For details about the increase in cases by year, see Measles Outbreaks.
A: 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.
A: 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, fully vaccinated people who get measles are much more likely to have a milder illness, and they are also 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.
A: No. People who received two doses of measles vaccine as children according to the U.S. vaccination schedule are considered protected for life and do not ever need a booster dose.
Adults need at least one dose of measles vaccine, unless they have evidence of immunity. Adults who are going to be in a setting that poses a high risk for measles transmission, including students at post-high school education institutions, healthcare personnel, and international travelers, should make sure they have had two doses separated by at least 28 days.
If you’re not sure whether you were vaccinated, talk with your doctor. More information about who needs measles vaccine.
A: You are considered protected from measles if you have written documentation (records) showing at least one of the following:
- You received two doses of measles-containing vaccine, and you are a(n)—
- school-aged child (grades K-12)
- adult who was not vaccinated as a child and will be in a setting that poses a high risk for measles transmission, including students at post-high school education institutions, healthcare personnel, and international travelers.
- You received one dose of measles-containing vaccine, and you are a(n)—
- preschool-aged child
- adult who was not vaccinated as a child and will not be in a high-risk setting for measles transmission.
- A laboratory confirmed that you had measles at some point in your life.
- A laboratory confirmed that you are immune to measles.
- You were born before 1957.
A: If you’re unsure whether you’re immune to measles, you should first try to find your vaccination records or documentation of measles immunity. If you do not have written documentation of measles immunity, 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).Top of Page
Q: How common was measles in the United States before the vaccine?
A: Before the measles vaccination program started in 1963, we estimate that about 3 to 4 million people got measles each year in the United States. Of those people, 400 to 500 died, 48,000 were hospitalized, and 4,000 developed encephalitis (brain swelling) from measles.
A: Yes. Since measles is still common in many countries, this disease will continue to be brought into the United States. 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.
A: Yes, it is possible that measles could become endemic (constant presence of a disease in an area) in the United States again, especially if vaccine coverage levels drop. This can happen when people
- forget to get vaccinated on time,
- don’t know that they need a vaccine dose (this is most common among adults), or
- refuse vaccines for religious, philosophical or personal reasons.
Research shows that people who refuse vaccines tend to group together in communities. When measles gets into communities with pockets of unvaccinated people, outbreaks are more likely to occur. These communities make it difficult to control the spread of the disease and make us vulnerable to having the virus re-establish itself in our country.
High sustained measles vaccine coverage and rapid public health response are critical for preventing and controlling measles cases and outbreaks.
A: Overall, nationally, the rates of people vaccinated against measles have been very stable since the Vaccines for Children (VFC) program was introduced in 1994. In 2013, the overall national coverage for MMR vaccine among children aged 19—35 months was 91.9%. However, MMR vaccine coverage levels continue to vary by state. For example, in 10 states, 95% of the children aged 19–35 months in 2013 had received at least one dose of MMR vaccine, while in 17 other states, less than 90% of these children were vaccinated against measles. At the county or lower levels, vaccine coverage rates may vary considerably. Pockets of unvaccinated people can exist in states with high vaccination coverage, underscoring considerable measles susceptibility at some local levels.
For more information about 2013 childhood vaccination coverage, see a CDC MMWR.
A: Yes, it's possible. The first step is to eliminate measles from each country and region of the world. Once this happens, there will be no place from which measles can spread.
All member states in the six World Health Organization regions have committed to eliminating measles by the year 2020. Once a disease has been eliminated from every country, it is considered "eradicated" from the world. See the Measles and Rubella Initiative for more information.
A: State and local health departments have the lead in investigating measles cases and outbreaks when they occur. CDC helps and supports health departments in these investigations by—
- communicating with public health officials from states with reported measles cases and providing technical assistance.
- gathering data reported by states on confirmed measles cases and evaluating and monitoring these data from a national perspective.
- testing specimens for difficult diagnostic cases of suspected measles infection when requested by states.
- using Advanced Molecular Detection (AMD) methods to determine measles virus genotypes and strains.
- providing rapid assistance on the ground during outbreak investigations, often through a formal request by the state health department.
- investing in state and local health departments for public health infrastructure and laboratory capacity to support front-line response to suspected and confirmed measles cases.
- alerting clinicians, healthcare facilities, and public health officials around the country about current outbreaks and providing vaccine policy and clinical guidance for healthcare providers.
- providing information to public and healthcare providers through a variety of media including the CDC website.
More information about the surveillance of vaccine-preventable diseases, like measles.
A: When an unvaccinated person gets measles, the infection is caused by wild-type measles virus. Wild-type measles viruses are divided into genetic groups called genotypes. Of 24 known genotypes, the World Health Organization (WHO) lists 11 genotypes that are known to currently circulate and are most commonly seen: B2, B3, D4, D5, D6, D7, D8, D9, D10, D11, G3, H1.
A: The genotype is identified in a laboratory using a method called nucleic acid sequencing. The genotype is based on the RNA (ribonucleic acid) sequence of the measles virus that caused the disease in an infected person. Learn about Genetic Analysis of Measles Viruses.Top of Page
- Page last reviewed: January 29, 2015
- Page last updated: October 19, 2015
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