than one per million vaccinations (<0.0001%). in developing countries where measles is common, the world health organization (who) recommends two doses of vaccine be given, at six and nine months of age. the vaccine should be given whether the child is hiv-infected or not. the vaccine is less effective in hiv-infected infants than in the general population, but early treatment with antiretroviral drugs can increase its effectiveness. measles vaccination programs are often used to deliver other child health interventions as well, such as bed nets to protect against malaria, antiparasite medicine and vitamin a supplements, and so contribute to the reduction of child deaths from other causes. the advisory committee on immunization practices (acip) recommends that all adult international travelers who do not have positive evidence of previous measles immunity receive two doses of mmr vaccine before traveling, although birth before 1957 is presumptive evidence of immunity. those born in the united states before 1957 are likely to have been naturally infected with measles virus and generally need not be considered susceptible. there have been false claims of an association between the measles vaccine and autism; this incorrect concern has reduced the rate of vaccination and increased the number of cases of measles where immunization rates became too low to maintain herd immunity. additionally, there have been false claims that measles infection protects against cancer. administration of the mmr vaccine may prevent measles after exposure to the virus (post-exposure prophylaxis). post-exposure prophylaxis guidelines are specific to jurisdiction and population. passive immunization against measles by an intramuscular injection of antibodies could be effective up to the seventh day after exposure. compared to no treatment, the risk of measles infection is reduced by 83%, and the risk of death by measles is reduced by 76%. however, the effectiveness of passive immunization in comparison to active measles vaccine is not clear. the mmr vaccine is 95% effective for preventing measles after one dose if the vaccine is given to a child who is 12 months or older; if a second dose of the mmr vaccine is given, it will provide immunity in 99% of children. there is no evidence that the measles vaccine virus can be transmitted to other persons. treatment there is no specific antiviral treatment if measles develops. instead the medications are generally aimed at treating superinfections, maintaining good hydration with adequate fluids, and pain relief. some groups, like young children and the severely malnourished, are also given vitamin a, which acts as an immunomodulator that boosts the antibody responses to measles and decreases the risk of serious complications. medications treatment is supportive, with ibuprofen or paracetamol (acetaminophen) to reduce fever and pain and, if required, a fast-acting medication to dilate the airways for cough. as for aspirin, some research has suggested a correlation between children who take aspirin and the development of reye syndrome. the use of vitamin a during treatment is recommended to decrease the risk of blindness; however, it does not prevent or cure the disease. a systematic review of trials into its use found no reduction in overall mortality, but two doses (200 000 iu) of vitamin a was shown to reduce mortality for measles in children younger than two years of age. it is unclear if zinc supplementation in children with measles affects outcomes as it has not been sufficiently studied. there are no adequate studies on whether chinese medicinal herbs are effective. prognosis most people survive measles, though in some cases, complications may occur. about 1 in 4 individuals will be hospitalized and 1–2 in 1000 will die. complications are more likely in children under age 5 and adults over age 20. pneumonia is the most common fatal complication of measles infection and accounts for 56-86% of measles-related deaths. possible consequences of measles virus infection include laryngotracheobronchitis, sensorineural hearing loss, and—in about 1 in 10,000 to 1 in 300,000 cases—panencephalitis, which is usually fatal. acute measles encephalitis is another serious risk of measles virus infection. it typically occurs two days to one week after the measles rash breaks out and begins with very high fever, severe headache, convulsions and altered mentation. a person with measles encephalitis may become comatose, and death or brain injury may occur. for people having had measles, it is rare to ever have a symptomatic reinfection. the measles virus can deplete previously acquired immune memory by killing cells that make antibodies, and thus weakens the immune system, which can cause deaths from other diseases. suppression of the immune system by measles lasts about two years and has been epidemiologically implicated in up to 90% of childhood deaths in third world countries, and historically may have caused rather more deaths in the united states, the uk and denmark than were directly caused by measles. although the measles vaccine contains an attenuated strain, it does not deplete immune memory. epidemiology main article: epidemiology of measles deaths from measles per million persons in 2012 0 1–8 9–26 27–38 39–73 74–850 disability-adjusted life year for measles per 100,000 inhabitants in 2004 no data ≤ 10 10–25 25–50 50–75 75–100 100–250 250–500 500–750 750–1000 1000–1500 1500–2000 ≥ 2000 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. reported cases who-region 1980 1990 2000 2005 2014 african region1,240,993481,204520,102316,22471,574 region of the americas257,790218,5791,7556619,898 eastern mediterranean region341,62459,05838,59215,06928,031 european region851,849234,82737,42137,33216,899 southeast asia region199,535224,92561,97583,627112,418 western pacific region1,319,640155,490176,493128,016213,366 worldwide4,211,4311,374,083836,338580,287462,186 even in countries where vaccination has been introduced, rates may remain high. measles is a leading cause of vaccine-preventable childhood mortality. worldwide, the fatality rate has been significantly reduced by a vaccination campaign led by partners in the measles initiative: the american red cross, the united states cdc, the united nations foundation, unicef and the who. globally, measles fell 60% from an estimated 873,000 deaths in 1999 to 345,000 in 2005. estimates for 2008 indicate deaths fell further to 164,000 globally, with 77% of the remaining measles deaths in 2008 occurring within the southeast asian region. there were 142,300 measles related deaths globally in 2018, of which most cases were reported from african and eastern mediterranean regions. these estimates were slightly higher than that of 2017, when 124,000 deaths were reported due to measles infection globally. in 2000, the who established the global measles and rubella laboratory network (gmrln) to provide laboratory surveillance for measles, rubella, and congenital rubella syndrome. data from 2016 to 2018 show that the most frequently detected measles virus genotypes are decreasing, suggesting that increasing global population immunity has decreased the number of chains of transmission. cases reported in the first three months of 2019, were 300% higher than in the first three months of 2018, with outbreaks in every region of the world, even in countries with high overall vaccination coverage where it spread among clusters of unvaccinated people. the numbers of reported cases as of mid-november is over 413,000 globally, with an additional 250,000 cases in drc (as reported through their national system), similar to the increasing trends of infection reported in the earlier months of 2019, compared to 2018. in 2019, the total number of cases worldwide climbed to 869,770. the number of cases reported for 2020 is lower compare to 2019. according to the who, the covid-19 pandemic hindered vaccination campaigns in at least 68 countries, including in countries that were experiencing outbreaks, which caused increased risk of additional cases. europe incidence of and deaths due to measles in england and wales between 1940 and 2017 in england and wales, though deaths from measles were uncommon, they averaged about 500 per year in the 1940s. deaths diminished with the improvement of medical care in the 1950s but the incidence of the disease did not retreat until vaccination was introduced in the late 1960s. wider coverage was achieved in the 1980s with the measles, mumps and rubella, mmr vaccine. in 2013–14, there were almost 10,000 cases in 30 european countries. most cases occurred in unvaccinated individuals and over 90% of cases occurred in germany, italy, netherlands, romania, and united kingdom. between october 2014 and march 2015, a measles outbreak in the german capital of berlin resulted in at least 782 cases. in 2017, numbers continued to increase in europe to 21,315 cases, with 35 deaths. in preliminary figures for 2018, reported cases in the region increased 3-fold to 82,596 in 47 countries, with 72 deaths; ukraine had the most cases (53,218), with the highest incidence rates being in ukraine (1209 cases per million), serbia (579), georgia (564) and albania (500). the previous year (2017) saw an estimated measles vaccine coverage of 95% for the first dose and 90% for the second dose in the region, the latter figure being the highest-ever estimated second-dose coverage. in 2019, the united kingdom, albania, the czech republic, and greece lost their measles-free status due to ongoing and prolonged spread of the disease in these countries. in the first 6 months of 2019, 90,000 cases occurred in europe. americas as a result of widespread vaccination, the disease was declared eliminated from the americas in 2016. however, there were cases again in 2017, 2018, 2019, and 2020 in this region. united states