Complications associated with measles
Thirty to 40% of measles patients experience at least one complication. Complications are most commonly observed in young infants, adults
older than 20, pregnant women, and people who are immunocompromised or malnourished. Complications can include diarrhea, otitis
media, pneumonia, and acute encephalitis. Central nervous system complications are rarer and can include primary measles encephalitis
(1–3/1000), acute postinfectious encephalomyelitis (1/1000), and subacute sclerosing panencephalitis (SSPE) (4–11/100,000).6 SSPE is a
progressive degenerative disease leading to gradual cognitive decline and motor dysfunction. It develops on average about 7 years after initial
measles infection but can manifest up to 27 years after initial infection. Measles infection during pregnancy can lead to spontaneous abortion
or premature delivery.3
Trends in the United States
Before licensure of the measles vaccine in 1963, about 500,000 measles cases were reported annually in the United States. With the success
of the measles vaccine and a mass vaccination campaign, the incidence rate of measles decreased by approximately 95% in the 1970s–1980s.
However, significant increases in measles cases occurred from 1989 to 1991, during which some 55,000 cases and 123 measles-associated
deaths were reported. A primary contributor to this resurgence was low vaccination rates among toddlers.
Figure 2. Number of Measles Cases Reported by Year, United States: 1980–2017
Measles cases again declined after 1990–1991, with establishment of the federal Vaccines for Children program to decrease barriers to
vaccine access, and after the 1989 recommendation of a second MMR dose for all school-age children.
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Figure 3. Number of Measles Cases Reported by Year, Texas: 2007–2017