MMR Waning Immunity

Waning Immunity and the MMR Vaccine

Nearly 50% of Vaccinated Schoolchildren Can Become Infected with Measles

School Immunity

Nearly 50% of schoolchildren and most adults vaccinated with two doses of the MMR vaccine can still be infected with measles virus and spread it to others, even with mild or no symptoms of their own.1-4

Susceptibility to Measles in School

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= Vaccinated, susceptible to subclinical infection and spread of measles
35% of 7-year-olds
60% of 15-year-olds
>60% of adults
Subclinical measles infection: Cases can develop illness without rash, with or without symptoms that include fever, cough, sore throat, and diarrhea.

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=  Vaccinated, susceptible to clinical infection and spread of measles
Projected 33% of adults by age 24–26
Clinical measles infection: Cases develop illness with fever and rash, with other symptoms that can include cough, runny nose, and eye irritation.

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=  Vaccinated and immune
65% of 7-year-olds
40% of 15-year-olds
<40% of adults

DOES IMMUNITY FROM THE MMR VACCINE WANE OVER TIME?

Yes. In 2007, the Centers for Disease Control and Prevention (CDC) conducted a study on waning immunity after two doses of the measles, mumps and rubella (MMR) vaccine.1 The results, published in Archives of Pediatrics and Adolescent Medicine, show:

  • About 35% of vaccinated 7-year-olds are susceptible to subclinical infection with measles virus.
  • About 60% of vaccinated 15-year-olds are susceptible to subclinical infection with measles virus.
  • By age 24–26, a projected 33% of vaccinated adults are susceptible to clinical infection.

Consequently, nearly 50% of schoolchildren and most adults vaccinated with the MMR vaccine can still be infected with measles virus and spread it to others, even with mild or no symptoms of their own.1-4 (See figure above.)

WOULD ANOTHER BOOSTER SHOT SOLVE THE PROBLEM OF WANING MMR VACCINE IMMUNITY?

No. The CDC conducted another study in 2016, published in The Journal of Infectious Diseases, which concludes that a third dose (booster shot) of the MMR vaccine is short-lived, lasting only one year.5 The authors state:

MMR3 [a third dose of MMR] is unlikely to solve the problem of waning immunity in the United States… We did not find compelling data to support a routine third dose of MMR vaccine.”

Note: Children with measles antibody levels less than 900 mIU/mL are susceptible to subclinical infection with measles virus but not to clinical infection. About 35% of vaccinated children 7 years of age have a measles antibody level less than 900 mIU/mL. This level steadily declines through childhood, resulting in about 60% of children 15 years of age with a measles antibody level less than 900 mIU/mL. Consequently, nearly 50% of schoolchildren ([35%+60%]/2) and most adults (greater than 60%) are susceptible to infection with measles virus.1

These statements are intended for informational purposes only and should not be construed as personal medical advice.

© 2019 Physicians for Informed Consent, an independent 501(c)(3) nonprofit educational organization. Updated Dec 2019.