Measles is a highly contagious, acute viral human disease caused by the measles virus. The incubation period is approximately 10-12 days. Initial symptoms of measles are characterised by fever, cough, running nose, bloodshot eyes and tiny white spots inside the mouth. Two to four days later, measles rash develops on the face and spreads to the rest of the body before gradually fading out. Disease can lead to death particularly if it gives rise to complications such as pneumonia and diarrhoea, which is particularly common in undernourished populations. Measles mortality ranges from below 0.1% in high-income settings to above 10% in epidemic situations in resource-poor settings.
Measles transmission is primarily person-to-person via respiratory droplets or aerosolised droplets that contain the virus. There is no known animal reservoir or asymptomatic carrier state documented. There is no specific antiviral treatment for measles virus. However, vaccination is highly effective at preventing measles transmission, and is estimated to have prevented around 20 million deaths during 2000-2015.
The first measles vaccine was licensed in 1963. Today, a safer and more effective measles vaccine is available. Measles vaccine can give long-lasting immunity similar to that generated by natural recovery. WHO recommends two doses of routine vaccination (MCV1 and MCV2) for all children to ensure immunity and prevent outbreaks. Clinical evidence suggests that the effectiveness of measles vaccine is 85% for one-dose vaccination and 99% for two-dose vaccination.
Measles is still one of the leading causes of death among young children, especially children under the age of 5 in African and Asian countries that have low per capita incomes and weak health infrastructures. Under the WHO Global Vaccine Action Plan, measles was targeted for elimination in most WHO Regions by 2020. This would require populations to have high coverage of two doses of measles-containing vaccine; the second dose is delivered either through the routine programme or through mass measles campaigns called supplementary immunisation activities (SIAs), some of which are funded by Gavi, the Vaccine Alliance, either as preventive or reactive campaigns.