Decades ago, measles was a common childhood disease, and complications were also common. Around one-third of people who contract measles—and it was nearly ubiquitous at one time—get some other medical condition a a direct result. The most common of these is otitis media, or a middle ear infection, which may result in hearing loss. Other complications include pneumonia, bronchitis, and encephalitis; in many cases measles can even be fatal. Measles can also cause corneal ulceration and scarring, which could lead to diminished eyesight.
These complications are largely in the past, however, thanks to measles vaccination, which became available in 1963 in the United States and was almost universal after 1977. The measles vaccine provides immunity to 95 percent of children older than one year who receive a single dose, and most of the remaining five percent develop immunity after a second dose.
During the heyday of the disease, "measles parties" to allow infected children in a community to spread the disease to their uninfected neighbors—especially the girls, because women who get the disease as adults, particularly during pregnancy, are prone to miscarriage or to having children with birth defects—were common. Measles vaccination is the same basic principle, stimulating an immune response so the disease doesn’t affect adults, but in a more certain and concentrated way with less suffering involved.
Unfortunately, measles has recently had a resurgence. In the late 1990s, false controversy began to be sown over the safety and efficacy of vaccines, and the 610 cases reported last year were the first large harvest. As parents are delaying vaccinating their children against measles—such as by rejecting the measles-mumps-rubella combined vaccine in favor of getting the three immunizations separately and spaced out—or refusing entirely, communities across the United States are seeing a growing number of measles cases, despite the disease having been declared eradicated in the Americas in 2002. In 2014, there were more than 200 cases of measles reported in the country for the first time in 17 years.
Not all parents who don’t vaccinate fear the bogeyman of alleged safety issues; some interpret religious requirements as forbidding it, and some have genuine medical reasons they can’t. However, when almost all children are vaccinated, herd immunity protects those who are not. Herd immunity means if someone is infect, even a highly contagious disease such as measles has no place to go.