Although the measles vaccine contains an attenuated strain, it does not deplete immune memory. Epidemiology
Measles is extremely infectious and its continued circulation in a community depends on the generation of susceptible hosts by birth of children. In communities that generate insufficient new hosts the disease will die out. This concept was first recognized in measles by Bartlett in 1957, who referred to the minimum number supporting measles as the critical community size (CCS). Analysis of outbreaks in island communities suggested that the CCS for measles is around 250,000. To achieve herd immunity, more than 95% of the community must be vaccinated due to the ease with which measles is transmitted from person to person.In 2011, the WHO estimated that 158,000 deaths were caused by measles. This is down from 630,000 deaths in 1990. As of 2018, measles remains a leading cause of vaccine-preventable deaths in the world. In developed countries the mortality rate is lower, for example in England and Wales from 2007 to 2017 death occurred between two and three cases out of 10,000. In children one to three cases out of every 1,000 die in the United States (0.1–0.2%). In populations with high levels of malnutrition and a lack of adequate healthcare, mortality can be as high as 10%. In cases with complications, the rate may rise to 20–30%. In 2012, the number of deaths due to measles was 78% lower than in 2000 due to increased rates of immunization among UN member states.
Two years later, measles was responsible for the deaths of half the population of Honduras, and it has ravaged Mexico, Central America, and the Inca civilization.Between roughly 1855 and 2005, measles is estimated to have killed about 200 million people worldwide.The 1846 measles outbreak in the Faroe Islands was unusual for being well-studied. Measles had not been seen on the islands for 60 years, so almost no residents had any acquired immunity. Three-quarters of the residents got sick, and more than 100 (1–2%) died from it before the epidemic burned itself out. Peter Ludvig Panum observed the outbreak and determined that measles was spread through direct contact of contagious people with people who had never had measles.Measles killed 20 percent of Hawaiis population in the 1850s. In 1875, measles killed over 40,000 Fijians, approximately one-third of the population. In the 19th century, the disease killed more than half of the Great Andamanese population. Seven to eight million children are thought to have died from measles each year before the vaccine was introduced.In 1914, a statistician for the Prudential Insurance Company estimated from a survey of 22 countries that 1% of all deaths in the temperate zone were caused by measles. He observed also that 1–6% of cases of measles ended fatally, the difference depending on age (0–3 being the worst), social conditions (e.g. overcrowded tenements) and pre-existing health conditions.In 1954, the virus causing the disease was isolated from a 13-year-old boy from the United States, David Edmonston, and adapted and propagated on chick embryo tissue culture.