From the Guidelines
Breakthrough rubeola in vaccinated children is a rare occurrence, with greater than 99% of persons who receive two doses of measles vaccine developing serologic evidence of measles immunity. When breakthrough infections do happen, they are typically mild and noncommunicable, with symptoms being less severe compared to unvaccinated individuals 1. The measles vaccine produces an inapparent or mild infection, and 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
- The standard MMR (measles, mumps, rubella) vaccine is highly effective, with two doses providing long-term, probably lifelong immunity in most persons 1.
- Breakthrough infections usually occur due to primary vaccine failure or secondary vaccine failure, where immunity wanes over time, although this phenomenon appears to occur rarely and has little effect on measles transmission and the occurrence of outbreaks 1.
- Factors contributing to breakthrough infections may include improper vaccine storage, administration errors, or individual immune response variations.
- Children with breakthrough measles are less contagious than unvaccinated infected individuals, but they should still be isolated until 4 days after rash onset.
- Treatment for breakthrough measles remains supportive care, including rest, fluids, antipyretics for fever, and vitamin A supplementation in severe cases or for children with vitamin A deficiency.
Clinical Implications
The possibility of breakthrough infections should not deter from the vaccination strategy, as vaccination remains the most effective way to prevent measles and reduce its severity when breakthrough cases occur. Healthcare providers should continue to follow the recommended vaccination schedule and ensure proper vaccine storage and administration to minimize the risk of breakthrough infections 1.
From the Research
Breakthrough Rubeola in Vaccinated Children
- The effectiveness of the measles, mumps, rubella (MMR) vaccine in preventing rubella is 89% after one dose, as reported in a cohort study of 1621 children 2.
- The MMR vaccine has been shown to be effective in preventing measles, with a 95% effectiveness rate after one dose and a 96% effectiveness rate after two doses 2.
- However, there is evidence to suggest that the protective effect of the MMR vaccine may wane over time, highlighting the need for further research on the durability of immunity 2.
- A longitudinal study found that rubella-specific humoral immunity declines following MMR vaccination, although antibody titers remain above the threshold for protective immunity 3.
- The combination MMRV (measles, mumps, rubella, and varicella) vaccine has been shown to have comparable immunogenicity and safety profiles to the MMR vaccine, with the exception of a higher incidence of fever and measles/rubella-like rash 4.
Vaccine Effectiveness and Safety
- The MMR vaccine has been found to be safe and effective in preventing measles, mumps, and rubella, with no evidence of an association with encephalitis, encephalopathy, or autistic spectrum disorders 2.
- However, there is evidence to suggest an association between MMR vaccination and febrile seizures, with an estimated attributable risk of 1 per 1700 to 1 per 1150 administered doses 2.
- The MMRV vaccine has been found to have a similar safety profile to the MMR vaccine, with the exception of a higher incidence of fever and measles/rubella-like rash 4.
Durability of Immunity
- The durability of humoral immunity to the rubella component of the MMR vaccine has been found to decline over time, although antibody titers remain above the threshold for protective immunity 3.
- Further research is needed to define the clinical correlates of protection based on neutralizing antibody titer and memory B cell response 3.