Be aware of the long-term consequences of measles in infants and children

Measles is a highly contagious acute febrile rash associated with significant acute morbidity and mortality in high-risk groups, including young children, pregnant women and immunocompromised persons. Acute, complicated courses may require hospitalization. Resolution of the rash often signals recovery and the end of the acute illness. However, infection can cause sustained morbidity from prolonged immune suppression and delayed neurologic disease months to years later.More than 5,000 cases of measles were reported in 2024–2025 in Canada, with more than 70% of cases occurring in children. Based on these figures, the anticipated cumulative morbidity from post-measles immunosuppression is expected to be high. Understanding and anticipating the long-term immune and neurologic consequences of measles, particularly in infants and young children, is essential for clinical care, surveillance and prevention strategies.The potential long-term consequences of measles are highlighted below.Immunosuppression and susceptibility to infectionMeasles infection can lead to immune amnesia, a type of prolonged immunosuppression that erases preexisting B- and T-cell memory and increases susceptibility to serious infections for months to years after recovery. The youngest children, especially those who are unimmunized, are at greatest risk.Children recovering from measles may once again become susceptible to infections they were previously protected against. Restoration of immune memory can take months to years. Mortality from nonmeasles infectious diseases remains elevated for up to two to three years post-measles infection.In addition, maternal memory cells can be erased following maternal measles, limiting the quality of passive immunity available to protect newborns and young infants during the early months of life when vulnerability to infections is highest.Overall, the downstream effects of measles on the infant and maternal immune system increase the risk for childhood infections and mortality. In undervaccinated communities, measles outbreaks may be associated with surges in invasive diseases such as pneumonia and meningitis caused by vaccine-preventable pathogens such as Haemophilus influenzae and Streptococcus pneumoniae. Post-measles preventive care should include increased vigilance for invasive infections.Persistent viral infection and neurologic complicationsMeasles can also cause severe neurologic complications, including encephalitis and acute disseminated encephalomyelitis. Delayed complications from chronic persistent central nervous system measles infection include measles inclusion body encephalitis, typically seen in immunocompromised patients within a year of infection, and subacute sclerosing panencephalitis (SSPE), a rare, frequently fatal disorder usually occurring six to 11 years after primary infection. Measles infection in the first two years of life carries a markedly higher risk of SSPE than infection at older ages and demonstrates a much shorter latency.Congenital measles Overall mortality has been rare in the current Canadian outbreak (2 deaths of 5,008 outbreak cases in 2025). However, disproportionately high mortality has been noted among reported cases of congenital measles (11% in Ontario; 10.5% nationally). SummaryMeasles is more than just an acute illness. It causes clinically meaningful immune injury, disproportionately affecting the youngest, and increases vulnerability to serious invasive infections. Neurological sequelae, although rare, occur at a higher incidence if measles occurs early in life (especially in utero). The unwanted long-term impact of measles reinforces the importance of measles immunization as the key strategy to prevent these long-term consequences.Reference:Barton M, Forbes A, Chyn S, et al. Beyond the rash: The long-term consequences of vertically and horizontally acquired measles in infants and children. JAMMI Canada 2026; published online May 27, 2026. (accessed June 4, 2026).

Be aware of the long-term consequences of measles in infants and children

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