How Effective is Measles Vaccine?
The CDC estimates that measles antibodies develop in approximately 98 percent of children vaccinated at 15 months or older. It is estimated that about 2-5 percent of children, who receive the vaccine at 12 months of age or younger or who only get one dose of MMR, fail to be protected. A second dose or MMR is thought to stimulate a protective immune response in about 99 percent of vaccine recipients.
The CDC says that vaccine-induced immunity “appears to be long-term and probably lifelong in most persons.” However, some studies show that vaccine failure due to waning immunity may occur.1 Recent news reports from India showed that only 1 child in 5 vaccinated for measles was actually protected from getting the disease, even after being fully vaccinated.2
According to the Merck product information insert, there is some evidence that if infants born to mothers, who have experienced natural measles infection, are vaccinated at less than one year of age, they may not develop long lasting vaccine acquired antibodies because natural maternal antibodies interfere with vaccine induced antibodies.3
Measles vaccine acquired immunity is reported to wane in at least 5 percent of cases, within 10 to 15 years after vaccination.4,5,6 A report published in 2012 by the Cochrane Collaboration reviewed 57 clinical trials and studies that involved about 14.7 million children vaccinated with the MMR vaccine.7 Cochrane found that:
"Based on the evidence provided by three cohort studies (3104 participants), vaccination with one dose of MMR vaccine is at least 95 percent effective in preventing clinical measles among preschool children; in schoolchildren and adolescents at least one dose of MMR vaccine was 98 percent effective in preventing laboratory-confirmed measles cases; one or two MMR doses were respectively 92 percent and 95 percent effective in preventing secondary measles cases."
There are studies showing that measles outbreaks can occur in fully vaccinated populations.8,9,10 For example, an outbreak of measles in the spring of 1985 in Corpus Christi, Texas, occurred in a school where more than 99 percent of the students were fully vaccinated. After examining serum samples from students for detectable measles antibodies, the study’s researchers concluded that “outbreaks of measles can occur in secondary schools, even when more than 99 percent of the students have been vaccinated…”11
In another outbreak in a school in Illinois in 1983-84, the Centers for Disease Control confirmed that the school had a “documented immunization level of 100 percent,"12 suggesting the possibility of certain amount of primary vaccine failure or waning immunity since it had been 10 or more years since the students, who got measles, had had their last measles shot.
Some research reveals that exposure to natural measles not only is actually necessary to maintain protective antibodies in vaccinated persons, but also may help prevent symptoms of allergic diseases.13,14 Still other research shows that measles vaccine acquired immunity wanes over time, providing an opportunity for subclinical (asymptomatic) measles infections to occur in fully vaccinated populations.15
IMPORTANT NOTE: NVIC encourages you to become fully informed about Measles and the Measles vaccine by reading all sections in the Table of Contents , which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.
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5 Markowitz LE, Preblud SR, Fine PE, Orenstein WA. Duration of Live Measles Vaccine-Induced Immunity. Pediatr Infect Dis J. 1990; 9:101-110.