From the Guidelines
The likelihood of catching measles if vaccinated as a child is very low, with greater than 99% of persons who receive two doses of measles vaccine developing serologic evidence of measles immunity. The measles vaccine, typically given as part of the MMR vaccine, is highly effective in producing long-term, probably lifelong, immunity in most persons 1. According to the study, measles antibodies develop among approximately 95% of children vaccinated at age 12 months and 98% of children vaccinated at age 15 months 1. Key points to consider include:
- The vaccine induces long-term immunity, with most vaccinated persons showing an anamnestic immune response upon revaccination, indicating that they are probably still immune 1
- Immunity can wane after successful vaccination, but this phenomenon appears to occur rarely and has little effect on measles transmission and the occurrence of outbreaks 1
- Even in the rare cases where vaccinated individuals do contract measles, they typically experience a milder form of the illness with fewer complications The protection from childhood vaccination is generally long-lasting, often providing immunity for life, though immunity may wane slightly over decades 1. Overall, the high level of protection provided by the measles vaccine is why widespread vaccination has been so successful in reducing measles cases worldwide and why maintaining high vaccination rates is essential for community protection.
From the Research
Measles Vaccination Effectiveness
The likelihood of catching measles if vaccinated as a child is significantly reduced due to the effectiveness of the measles vaccine.
- According to a study published in 2013 2, the Advisory Committee on Immunization Practices (ACIP) recommends 2 doses of MMR vaccine routinely for children, which provides adequate immunity against measles.
- A study published in 2017 3 found that the effectiveness of MMR vaccine post-exposure prophylaxis was 83.4% in preventing measles among nonimmune contacts aged <19 years.
- Another study published in 2017 4 highlighted the importance of measles vaccination in preventing the disease, with major reductions in measles incidence and mortality achieved through widespread use of the vaccine.
Vaccine-Induced Immunity
Vaccine-induced immunity plays a crucial role in preventing measles.
- A study published in 2023 5 provided practical guidance for clinicians on when to use serologic testing to determine measles immunity, emphasizing the importance of adequate immunity.
- The same study 5 noted that sometimes, individuals may not achieve seroconversion after 2 doses of the MMR vaccine, raising questions about adequate immunity.
Transmission of Measles Vaccine Virus
There is no evidence of human-to-human transmission of the live attenuated measles vaccine virus.
- A systematic review published in 2016 6 found no evidence of genotypic confirmation of a vaccine virus transmitted from a recently vaccinated individual to a susceptible close contact.
- This review 6 suggests that the live attenuated measles vaccine virus is poorly adapted to replicating in human tissue, making human-to-human transmission unlikely.