Measles resurgence in the United States

Measles was declared eliminated from the United States in 2000 by the World Health Organization due to the success of vaccination efforts.^[1] However, it continues to be reintroduced by international travelers,^[1] and in recent years, anti-vaccination sentiment has allowed for the reemergence of measles outbreaks.^[2][3]

In 2018, 371 cases of measles were confirmed in the United States. From January to August 2019, 1215 cases across 30 states had been confirmed as measles by the Centers for Disease Control and Prevention (CDC).^[4] This is the largest number of cases in one calendar year since the disease was declared eliminated.^[5] In 2019, a state of emergency was declared in New York City^[6] and Washington^[7] in response to the extremely contagious disease. There is concern that the World Health Organization (WHO) may rescind the U.S.'s measles elimination status.^[8]

The vast majority of people infected had not received vaccination and were living in close-knit communities where the immunization rate is lower than average.^[9] The director of the National Institutes of Health wrote in 2016 that parents refusing to vaccinate their children were leading to outbreaks of preventable diseases, including measles.^[10] The World Health Organization also reported that the rise in measles is a direct result of anti-vaccination movements.^[11] The recommended measles vaccination protocol is to receive two doses, at least one month apart. One dose of the vaccination is 93 percent effective at preventing measles, while two doses is 97 percent effective.^[12]

Measles is one of the most contagious of infectious diseases.^[13] If not immunized, a person exposed to someone with measles has a 95% chance of becoming infected. During the early stage of an outbreak in an unvaccinated population, each infected person spreads the disease to an average of 12 to 18 other people.^[14]