Sorting Out the MMR Hype
By Christine Climer
What’s the big deal about the measles-mumps-rubella (MMR) vaccination? Can it really cause autism? Are the diseases it vaccinates against really so bad? Whose studies should you believe?
The best way to figure out whether or not your children need this controversial shot is to take an objective look at the facts from both sides of the table.
A quick history of the MMR
The measles-mumps-rubella (MMR) vaccine was licensed for use in 1971, but the first time it was recommended as the preferred vaccine for children was in 1977. This appears to have been implemented in order to increase vaccination rates for mumps and rubella.
Prior to that 1977 recommendation (and even for several years thereafter), not all doctors used the same measles, mumps and rubella vaccines. Each of the three was available as an individual vaccine beginning in the mid 1960s, and combinations using two of the three viruses were soon developed. Some doctors were hesitant to inject three live virus vaccines simultaneously, so the transition to the MMR was a gradual one.
Originally, one dose of MMR was supposed to offer life-long immunity to all three illnesses. The United States experienced an increase in the number of measles cases reported in the mid-1980s; approximately 68% of those cases reported in school-aged children had been appropriately vaccinated. So in 1989, recommendations added a second MMR to the schedule, because one measles dose was not effective as originally thought. Parents today often ask why all three vaccines must be given again if only the measles component requires a second dose.
What is rubella?
According to the Centers for Disease Control (CDC), rubella is so mild that it is often overlooked or misdiagnosed. The most common symptoms include swollen lymph nodes, joint pain, rash and low-grade fever. About half of rubella infections produce no symptoms at all. Arthritis occurs commonly in infected women; arthritis is a more common side effect from the vaccine when it is given to teenage girls and women.
The reason children are vaccinated against rubella is so that they will not spread the illness to susceptible pregnant women — not because the disease itself poses any significant risk to children. If a woman has never had rubella or has inadequate immunity and becomes infected during pregnancy, there is about a 10% chance her baby might be born with congenital rubella syndrome. Women of childbearing age may wish to have blood tests performed before becoming pregnant to determine if they still have protective antibody levels from childhood.
What is mumps?
Mumps is generally a mild illness. One-third of cases have no detectable symptoms -- infected people do not even know they are sick. The swollen jaws that most of us associate with mumps actually only occur in about 30% of infected individuals. According to the CDC, mild central nervous system irritation (causing headache and stiff neck) can appear in about 15% of cases, but permanent damage is rare.
Inflammation of the testicles (usually only on one side) occurs in about half of infected males who have already been through puberty. Contrary to what many people believe, sterility is a very rare occurrence among these cases.
What is measles?
Looking back at the vaccination recommendations made over the past 25 years, measles was the only one of the three illnesses that the CDC ever spoke very seriously about. Measles typically starts with fever, cold-like symptoms and a rash. Other common symptoms include swollen lymph nodes, anorexia and diarrhea.
In industrialized countries such as the United States, complications occur in around 10-15% of cases and are most common in children under 5 years of age and in adults over 20. Diarrhea is the most common complication, followed by ear infections and pneumonia. Low vitamin A status has been associated with a higher rate of complications.
What’s in the MMR vaccine?
The MMR vaccine contains live viruses. They are “weakened” by growing them repeatedly in either chick embryo or “WI-38” cells. Because viruses change slightly to adapt to their growing environments, they become a little less able to cause the diseases we associate with them in humans.
Some parents and scientists question how these small changes might add up over time:
Are any analyses done routinely to monitor these changes in the viruses?
If so, what is done and how often? Are the results validated by anyone other than the vaccine manufacturer?
If a vaccine strain virus has a cell receptor that is different from the wild virus, does that mean it is more likely to infect certain types of cells?
Do the safety and efficacy studies done 35 years ago to obtain FDA licensure still mean the same thing today, since the viruses change slightly over time?
Some parents also face an ethical dilemma with the MMR vaccine. The rubella virus is passed through WI-38 cells. These cells were derived from aborted fetal tissue obtained from a legal abortion in the 1960s. Many parents feel unable to accept this particular vaccine, as their religious beliefs do not allow them to participate in or condone abortions in any way. Other MMR ingredients that may conflict with religious or moral beliefs are human albumin (a blood protein) and fetal bovine serum (the liquid portion of blood from fetal cows).
The MMR also contains small amounts of gelatin, egg and neomycin. Anyone who has a history of allergy to these ingredients should speak with their health care provider prior to receiving a dose of this vaccine.
Each of the three components of the MMR is manufactured as an individual vaccine, but availability is frequently limited. Speak with your health care provider if you are interested in exploring this dosage option.
Is the MMR vaccine effective?
No vaccine is ever 100% effective. How effective it is depends on many factors such as:
your child’s unique immune response
whether the vaccine was properly stored and administered
the age and condition of your child when he or she received the vaccine
whether your child is ever exposed to circulating viruses which have a “booster” effect
Disease incidence certainly seems to have decreased for all three illnesses since vaccines became available, but outbreaks continue to occur. For example, a 2003 measles outbreak in a Pennsylvania boarding school produced nine documented cases. Of those nine students, six had received two doses of measles containing vaccine, one had received only one dose and two were unvaccinated. The student who initiated the outbreak contracted the illness while traveling to Lebanon. He had received two doses of the vaccine. The only complications noted for this outbreak were two cases of dehydration.
As there become fewer people in our communities with measles, vaccinated children have fewer chances to be exposed to the illness; therefore, they lose natural immune boosting to measles as they grow up. Vaccination also results in lower antibody levels than does natural measles infection, so vaccinated mothers pass on less protection to their babies. Those babies become susceptible to measles at an earlier age than babies born to mothers who have natural measles immunity. Both of these factors contribute to disease susceptibility during the two periods of life when complications are most likely to occur.
What about side effects?
Because the MMR is a live virus vaccine, it has the potential to cause some of the same effects as the wild type viruses. The wide range of possible side effects includes swelling, rash, fever, arthritis, respiratory infection and nervous system disorders. More detailed information may be found beginning on page six of the prescribing information.
Many parents are concerned about the potential connection between regressive autism and either thimerosal (a mercury containing preservative) or MMR. The MMR is not and never has been preserved with thimerosal, though other childhood vaccines either did or still do contain thimerosal. The Institute of Medicine just released a report citing no connection between either thimerosal or MMR and autism, but the study has received much criticism from advocacy groups, politicians and scientists. With controversy on both sides of the fence, this issue will not be resolved any time soon.
What if my child gets sick?
For all three of these illnesses, simple home care measures go a long way. Make sure your child gets plenty of rest and drinks lots of fluids. More helpful tips are available in our archives. Some doctors give children with measles vitamin A supplements, and zinc supplementation has been found to be helpful in children with pneumonia or diarrhea.
If you have any concerns or questions about the MMR vaccine or any of the illnesses, always call and speak with your health care provider.
References
1. Bitsch M. Rubella in pregnant Danish women 1975-1984. Dan Med Bull. 1987 Mar;34(1):46-9.
2. Brooks WA, Yunus M, Santosham M, Wahed MA, Nahar K, Yeasmin S, Black RE. Zinc for severe pneumonia in very young children: double-blind placebo-controlled trial. Lancet. 2004 May 22;363(9422):1683-8.
3. CDC. Congenital Rubella Syndrome Among the Amish -- Pennsylvania, 1991-1992. MMWR 1992; 41(26):468-469,475-476.
5. CDC. Epidemiology and Prevention of Vaccine-Preventable Diseases, 8th Edition online version.
6. CDC. Measles Outbreak in a Boarding School --- Pennsylvania, 2003. MMWR 2004; 53(14):306-309.
7. CDC, National Immunization Program. “Vaccine Safety Issues of Interest”.
8. CDC. Recommendation of the Immunization Practices Advisory Committee (ACIP): Measles Prevention. MMWR 1982; 31(17):217-24.
9. CDC. Recommendations of the Immunization Practices Advisory Committee (ACIP): Measles Prevention. MMWR 1989; 38(S-9):1-18.
10. CDC. Recommendation of the Immunization Practices Advisory Committee: Mumps Vaccine. MMWR 1982; 31(46):617-20,625-7.
11. CDC. Recommendation of the Immunization Practices Advisory Committee (ACIP): Rubella Prevention. MMWR 1984; 33(22): 301-10,315-8.
12. CDC. Recommendation of the Public Health Service Advisory Committee on Immunization Practices: mumps vaccine. MMWR 1977;26:393-4.
13. Institute of Medicine. Immunization Safety Review: Vaccines and Autism.
14. Mahalanabis D, Bhan MK. Micronutrients as adjunct therapy of acute illness in children: impact on the episode outcome and policy implications of current findings. Br J Nutr. 2001 May;85 Suppl 2:S151-8.
15. Manchester M, Eto DS, Valsamakis A, Liton PB, Fernandez-Munoz R, Rota PA, Bellini WJ, Forthal DN, Oldstone MB. Clinical isolates of measles virus use CD46 as a cellular receptor. J Virol. 2000 May;74(9):3967-74.
16. Merck & Co., Inc. Merck Manual of Diagnosis and Therapy (Online Version).
17. Merck & Co., Inc. Prescribing Information.
18. Mossong J, Nokes DJ, Edmunds WJ, Cox MJ, Ratnam S, Muller CP. Modeling the impact of subclinical measles transmission in vaccinated populations with waning immunity. Am J Epidemiol 1999 Dec 1;150(11):1238-49.
19. NVIC press release National Vaccine Information Center Says IOM Played Politics in Report on Autism and Vaccines.
20. Paunio M, Hedman K, Davidkin I, Valle M, Heinonen OP, Leinikki P, Salmi A, Peltola H. Secondary measles vaccine failures identified by measurement of IgG avidity: high occurrence among teenagers vaccinated at a young age. Epidemiol Infect 2000 Apr;124(2):263-71.
21. Texas Department of Health, Immunization Division. “Licensure Dates for Vaccines and Toxoids, United States.”
22. U.S. Representative Dave Weldon, MD, Website Content.
23. Woelk CH, Jin L, Holmes EC, Brown DW. Immune and artificial selection in the haemagglutinin (H) glycoprotein of measles virus. J Gen Virol. 2001 Oct;82(Pt 10):2463-74.
24. World Health Organization. WHO Guidelines for Epidemic Preparedness and Response to Measles Outbreaks. May 1999. Geneva, Switzerland.
© Christine Climer
Christine Climer is a registered nurse with experience in pulmonary disease, pediatrics, home health and hospice services. Also trained in early childhood education, she is currently executive director and child care nurse for an early childhood health promotion organization. She lives with her husband and three children (including a set of twins) in Texas and enjoys researching health issues and gardening.
