Measles, Mumps, and Rubella (MMR) Vaccines
Introduction to MMR Vaccine
The Measles, Mumps, and Rubella (MMR) vaccine is a combination vaccine that provides protection against three potentially serious viral diseases. It was first licensed in 1971 and has since become a cornerstone of childhood immunization programs worldwide.
- Measles: A highly contagious respiratory disease caused by the measles virus (genus Morbillivirus)
- Mumps: A viral infection affecting the salivary glands, caused by the mumps virus (genus Rubulavirus)
- Rubella: Also known as German measles, caused by the rubella virus (genus Rubivirus)
The MMR vaccine has played a crucial role in reducing the incidence of these diseases, with measles elimination achieved in many countries and significant reductions in mumps and rubella cases.
Vaccine Composition
The MMR vaccine is a live attenuated vaccine containing weakened strains of the measles, mumps, and rubella viruses. Common formulations include:
- Measles component: Derived from the Edmonston-Enders strain or Schwarz strain
- Mumps component: Usually the Jeryl Lynn strain or RIT 4385 strain (derived from Jeryl Lynn)
- Rubella component: Typically the Wistar RA 27/3 strain
Additional components may include:
- Stabilizers (e.g., sorbitol, hydrolyzed gelatin)
- Cell culture media residuals
- Antibiotics (trace amounts)
- pH adjusters
It's important to note that the vaccine does not contain thimerosal or other preservatives.
Administration
The MMR vaccine is administered subcutaneously, typically in the upper arm or thigh. The standard immunization schedule includes:
- First dose: 12-15 months of age
- Second dose: 4-6 years of age
Catch-up vaccination: Individuals who have not received the vaccine according to the standard schedule should be immunized as follows:
- Children and adolescents: Two doses at least 28 days apart
- Adults: At least one dose, with certain high-risk groups recommended to receive two doses
Storage and handling: The vaccine should be stored between 2°C and 8°C (35°F to 46°F) and protected from light. Once reconstituted, it should be used within 8 hours.
Efficacy
The MMR vaccine has demonstrated high efficacy in preventing the three targeted diseases:
- Measles:
- One dose: Approximately 93% effective
- Two doses: Approximately 97% effective
- Mumps:
- One dose: 78% effective (range: 49-92%)
- Two doses: 88% effective (range: 66-95%)
- Rubella:
- At least 95% effective after a single dose
Factors affecting efficacy may include:
- Age at vaccination
- Host immune status
- Proper storage and handling of the vaccine
- Circulating virus strains
Long-term studies have shown that immunity persists for decades in most individuals, although antibody levels may decline over time.
Adverse Events
The MMR vaccine is generally safe, but like all medical interventions, it can cause adverse events. These are typically mild and self-limiting:
Common adverse events:
- Injection site reactions (pain, redness, swelling): 10-25% of recipients
- Fever (≥39.4°C or 103°F): 5-15% of recipients
- Rash: About 5% of recipients
- Lymphadenopathy: Rare
Less common adverse events:
- Febrile seizures: 1 per 3,000-4,000 doses
- Transient arthralgia or arthritis (primarily in adult women): Up to 25% of adult women recipients
- Transient thrombocytopenia: Approximately 1 per 30,000 doses
- Parotitis: Rare
Very rare adverse events:
- Anaphylaxis: 1-3.5 per million doses
- Encephalitis or encephalopathy: Less than 1 per million doses
It's important to note that the risks associated with the vaccine are significantly lower than the risks of the diseases it prevents.
Contraindications
The following are absolute contraindications to MMR vaccination:
- Severe allergic reaction (e.g., anaphylaxis) to a previous dose or vaccine component
- Pregnancy
- Severe immunodeficiency (e.g., hematologic and solid tumors, chemotherapy, congenital immunodeficiency, long-term immunosuppressive therapy, or severely symptomatic HIV infection)
Precautions (situations where vaccination should be deferred until further evaluation):
- Moderate or severe acute illness
- Recent administration of blood products (specific interval depends on the product)
- Thrombocytopenia or history of thrombocytopenic purpura
- Personal or family history of seizures
False contraindications (conditions often mistakenly considered contraindications):
- Mild acute illness with or without fever
- Breastfeeding
- Allergy to eggs
- HIV infection without severe immunosuppression
- Undiagnosed autism or family history of autism
Special Populations
Healthcare Workers
Healthcare workers born in 1957 or later without evidence of immunity should receive two doses of MMR vaccine. Those born before 1957 are generally considered immune but may receive one dose if serologic testing indicates susceptibility.
International Travelers
Travelers aged ≥12 months should have documented evidence of immunity or receive MMR vaccination before departure. Infants aged 6-11 months should receive one dose before travel to high-risk areas.
Pregnant Women
MMR vaccine is contraindicated during pregnancy due to the theoretical risk of fetal harm. Women should avoid pregnancy for at least 28 days after vaccination. Inadvertent vaccination during pregnancy is not an indication for termination.
Immunocompromised Individuals
Severely immunocompromised persons should not receive MMR vaccine. Those with mild immunosuppression (e.g., HIV-infected persons with CD4 T-lymphocyte percentages ≥15%) may be vaccinated.
Outbreak Settings
During outbreaks, additional doses or altered schedules may be recommended:
- Measles: A third dose may be recommended in specific outbreak settings
- Mumps: A third dose may be considered in outbreak settings
Public Health Impact
The introduction of the MMR vaccine has had a profound impact on global public health:
Measles
- 79% reduction in measles deaths globally between 2000 and 2015
- Elimination (interruption of endemic transmission) achieved in many countries
- Prevented an estimated 21.1 million deaths between 2000 and 2017
Mumps
- 99% reduction in U.S. mumps cases compared to the pre-vaccine era
- Significant reductions in complications such as encephalitis and deafness
Rubella
- Elimination of endemic rubella transmission in the Americas (2015) and Europe (2016)
- Dramatic reduction in congenital rubella syndrome cases
Challenges
Despite these successes, challenges remain:
- Vaccine hesitancy and misinformation
- Maintaining high vaccination coverage in the face of perceived low disease risk
- Reaching under-served populations
- Continued transmission in some regions, posing a risk of importation to areas with elimination status
Continued vigilance, strong immunization programs, and public education are crucial to maintaining and extending the public health benefits of MMR vaccination.
Measles, Mumps, and Rubella (MMR) Vaccines
- What diseases does the MMR vaccine prevent?
Measles, Mumps, and Rubella - At what age is the first dose of MMR vaccine typically given?
12-15 months - When is the second dose of MMR vaccine typically given?
4-6 years - How many doses of MMR vaccine are required for full protection?
Two doses - What is the minimum interval between the two doses of MMR vaccine?
4 weeks - Can adults get the MMR vaccine?
Yes, if they don't have evidence of immunity - What is the efficacy of the MMR vaccine after two doses?
97% for measles, 88% for mumps, 97% for rubella - Can pregnant women receive the MMR vaccine?
No, it's contraindicated during pregnancy - What are common side effects of the MMR vaccine?
Fever, mild rash, temporary joint pain - Is the MMR vaccine a live vaccine?
Yes, it contains live attenuated viruses - Can the MMR vaccine be given with other vaccines?
Yes, it can be administered with other vaccines - Is there a combination vaccine that includes MMR?
Yes, the MMRV vaccine combines MMR with varicella - Can the MMR vaccine cause autism?
No, extensive research has found no link between MMR vaccine and autism - Who should not receive the MMR vaccine?
Pregnant women, people with severe immunodeficiency, and those allergic to vaccine components - What is the storage temperature for MMR vaccines?
-50°C to -15°C (-58°F to 5°F) before reconstitution - Can the MMR vaccine be given after exposure to measles?
Yes, if given within 72 hours of exposure, it may prevent or lessen the severity of measles - Is the MMR vaccine part of the routine childhood immunization schedule globally?
Yes, it's recommended by WHO for all national immunization programs - Can immunocompromised individuals receive the MMR vaccine?
Generally no, but it depends on the level of immunosuppression - What organization recommends MMR vaccination globally?
The World Health Organization (WHO) - In which year was the combined MMR vaccine first introduced?
1971 in the United States - How long does immunity from the MMR vaccine last?
Studies suggest lifelong immunity in most individuals - Can adults who received only one dose as children get a second dose?
Yes, it's recommended for certain high-risk groups - Is there a separate MMR vaccine for adults and children?
No, the same vaccine is used for all age groups - Can the MMR vaccine treat active measles, mumps, or rubella infections?
No, it's preventive and doesn't treat active infections - What percentage of people develop protective antibodies after two doses of MMR vaccine?
Over 99% for measles and rubella, about 88% for mumps - Is there a need for booster doses after completing the initial MMR vaccine series?
Generally no, but may be recommended in certain outbreak situations - Can the MMR vaccine be given to breastfeeding mothers?
Yes, it's safe for breastfeeding mothers - How soon after receiving the MMR vaccine can a woman become pregnant?
It's recommended to wait at least 4 weeks after vaccination - Can the MMR vaccine cause the diseases it's designed to prevent?
No, the attenuated viruses in the vaccine cannot cause the full diseases - Is the MMR vaccine effective against all strains of measles, mumps, and rubella?
Yes, it provides protection against all known strains
