Measles is a highly contagious viral illness that can be fatal. Although preventable, it remains a significant health threat globally. The virus spreads easily through the air when an infected person coughs or sneezes, and can live in the air for up to two hours. While many people recover within about 10 days, the infection can lead to severe and sometimes deadly outcomes.
Life-Threatening Complications from Measles
Pneumonia, an infection of the lungs, is the most common cause of death from measles, particularly in young children. This lung infection can be caused directly by the measles virus itself or by a secondary bacterial infection that takes hold because the virus has weakened the immune system. About one out of every 20 children with measles will develop pneumonia.
Another serious complication is encephalitis, which is swelling of the brain. This condition occurs in approximately one out of every 1,000 cases of measles and can lead to permanent brain damage, intellectual disability, deafness, or convulsions. For every 1,000 children who contract measles, one to three may die from these respiratory and neurologic complications.
The measles virus also causes “immune amnesia,” where the body loses its memory of how to fight off other infections it was previously immune to. This state of immunosuppression can last for weeks to months after the initial measles infection has resolved, leaving individuals vulnerable to other dangerous illnesses. This lingering vulnerability increases the risk of mortality for up to three years after having measles.
Delayed Fatal Neurological Disease
Beyond the immediate risks, a measles infection can lead to a rare but invariably fatal neurological disease years after the initial illness. This condition is known as Subacute Sclerosing Panencephalitis (SSPE). It is a degenerative disease of the central nervous system that typically develops seven to ten years after a person has recovered from measles. SSPE is caused by the persistence of the measles virus in the body long after the initial infection seems to have cleared.
The risk of developing SSPE is higher for individuals who contracted measles at a very young age, particularly before the age of two. The disease progresses slowly, causing a gradual decline in cognitive and motor functions. SSPE is distinct from the acute encephalitis that can occur during the initial measles infection.
Populations at Highest Risk
Certain groups of people are more susceptible to the severe and fatal complications of measles. Young children under the age of five are particularly vulnerable. Their developing immune systems are less equipped to handle the virus, making them more likely to suffer from complications like pneumonia. About one in five unvaccinated people in the U.S. who get measles requires hospitalization.
Adults over the age of 20 also face a higher risk of severe outcomes. Pregnant individuals who are not vaccinated are another high-risk group; measles can endanger their life and lead to premature birth or the loss of the baby. People with compromised immune systems, such as those with leukemia or HIV infection, are also at an elevated risk. Malnutrition, especially a deficiency in vitamin A, is another factor that increases the risk of severe measles.
The Role of Vaccination in Preventing Deaths
The most effective way to prevent measles and its deadly complications is through vaccination. The measles, mumps, and rubella (MMR) vaccine is a safe and highly effective tool for preventing infection. Widespread immunization has made measles much less common in many parts of the world, but outbreaks still occur, primarily among unvaccinated populations.
The MMR vaccine is typically given in two doses. This two-dose regimen provides robust protection against the virus. The vaccine works by preparing the body’s immune system to recognize and fight off the measles virus without causing the actual disease. By preventing the initial infection, vaccination eliminates the risk of developing severe complications like pneumonia, encephalitis, and the long-term threat of SSPE.