From the Guidelines
The risk of getting measles if you are vaccinated is very low, with two doses of the MMR vaccine providing about 97% protection against the disease. The measles vaccine is highly effective in preventing measles outbreaks among school-aged and older persons, as stated in the study by 1. This means that only about 3 out of 100 fully vaccinated people would get measles if exposed to the virus.
Key Points to Consider
- The MMR vaccine is the vaccine of choice when protection against measles, mumps, and rubella is required on or after the first birthday, unless any of its component vaccines is contraindicated, as recommended by 1.
- Two doses of measles vaccine are necessary to develop adequate population immunity to prevent measles outbreaks, according to 1.
- Even if a vaccinated person does contract measles, they typically experience a milder form of the illness with less severe symptoms and lower risk of complications.
- The vaccine works by stimulating your immune system to produce antibodies against the measles virus without causing the actual disease, providing long-term protection against future measles infections.
Recommendations for Vaccination
- For maximum protection, the standard recommendation is two doses of MMR vaccine, typically given at 12-15 months of age and again at 4-6 years.
- Adults born after 1957 who don't have evidence of immunity should get at least one dose of MMR vaccine, as this will help prevent outbreaks and protect vulnerable populations through herd immunity.
From the Research
Risk of Getting Measles if Vaccinated
The risk of getting measles if you are vaccinated is extremely low. According to a study published in 2013, the public health approach to contact tracing and exclusions for vaccine-associated measles in immunocompromised patients is unclear, but the rarity of secondary cases provides further evidence that the risk to the general public is likely extremely low 2.
Vaccine Effectiveness
- The effectiveness of measles vaccination is high, with two doses of measles, mumps, and rubella (MMR) vaccine being 97% effective against measles 3.
- A study published in 2017 found that the effectiveness of MMR post-exposure prophylaxis (PEP) was 83.4% (95% confidence interval [CI], 34.4%, 95.8%) 4.
- The same study found that the effectiveness of immune globulin (IG) PEP was 100% (approximated 95% CI, 56.2%, 99.8%) 4.
Immune Response
- A study published in 2002 found that a large proportion of pre-school children had measles and mumps IgG antibody below the putative level of protection 2-4 years after receiving a first dose of MMR vaccine 5.
- The same study found that a second dose of MMR vaccine significantly boosted antibody levels, with the proportion negative to one or more antigens dropping to <4% 5.
- A study published in 2016 found that most subjects were seropositive before receiving a third dose of MMR vaccine, and very few had a secondary immune response after receipt of the third dose 3.
Special Populations
- The Advisory Committee on Immunization Practices (ACIP) recommends 2 doses of MMR vaccine routinely for children, with the first dose administered at age 12 through 15 months and the second dose administered at age 4 through 6 years before school entry 6.
- ACIP also recommends 2 doses of MMR vaccine for adults at high risk for exposure and transmission, and 1 dose for other adults aged ≥18 years 6.