Short answers, pulled from the story.
Symptoms of measles typically appear 10-14 days after exposure. The first signs are fever, cough, runny nose, and inflamed eyes, sometimes referred to as the three C's: cough, coryza, and conjunctivitis. Small white spots called Koplik spots may appear inside the cheeks two to four days into the illness, and the characteristic red rash develops three to five days after symptoms begin.
Measles is among the most contagious human pathogens. Nine out of ten people who lack immunity and share living space with an infected person will become infected. The reproductive number has been estimated as broadly as 3.7 to 203.3 in different populations. The virus remains infectious in the air via respiratory droplets for up to two hours.
Measles immune amnesia is the destruction of the body's previously acquired immune memory. The measles virus kills memory cells that store antibodies built up against other infections over a lifetime. After recovery, the immune system generates new memory cells specific only to measles, erasing prior immunities. Population studies suggest this suppression continues for 2-3 years following infection.
John Enders and Thomas C. Peebles isolated the measles virus in 1954 from a 13-year-old named David Edmonston. Maurice Hilleman further developed the virus into a vaccine that became widely available in the United States in 1963. The MMR vaccine, licensed in 1971, is 95% effective after one dose and 97-99% effective after two doses. More than 95% of a community must be vaccinated to achieve herd immunity.
Measles deaths have fallen dramatically since the introduction of vaccines but remain significant. Deaths dropped from 2.6 million in 1980 to 73,000 by 2014 due to global vaccination programs. In 2022, an estimated 136,000 measles deaths occurred globally, mostly among unvaccinated or under-vaccinated children under age five. Pneumonia accounts for 56-86% of measles-related deaths.
The 2019 U.S. measles resurgence reached 1,282 confirmed cases in 31 states, the highest number since 1992. Most cases occurred in communities with low vaccination rates, including clusters in Orthodox Jewish neighborhoods in Brooklyn and Rockland County, New York, and in Clark County, Washington. Public health officials attributed the increase largely to parents choosing not to vaccinate their children.