Measles

Unique identifier / Notation

BI0221

Synonyms

Rubeola

Measles is a highly contagious, serious disease caused by a virus from the paramyxovirus family. It spreads easily when an infected person breathes, coughs or sneezes. It can cause severe disease, complications, and even death (adapted from WHO 2024).

Primary reference(s)

WHO, 2024. Measles. World Health Organization (WHO). Accessed 25 May 2025.

Annotations

Additional scientific description

Measles is a highly contagious viral disease which affects susceptible individuals of all ages and remains one of the leading causes of death among young children globally, despite the availability of safe and effective measles-containing vaccines. It is transmitted via droplets from the nose, mouth, or throat of infected persons. Initial symptoms, which usually appear 10 to 12 days after infection, include high fever, usually accompanied by one or more of the following: runny nose, conjunctivitis, cough and tiny white spots on the inside of the mouth. Several days later, a rash develops, starting on the face and upper neck and gradually spreads downwards. A patient is infectious four days before the start of the rash to four days after the appearance of the rash. Most people recover within two to three weeks (WHO, 2019).

Before the introduction of the measles vaccine in 1963 and widespread vaccination, major epidemics occurred approximately every two to three years and caused an estimated 2.6 million deaths each year (WHO, 2024).

Serious complications are more common in children under the age of 5 years, or in adults over the age of 30 years. The most serious complications include blindness, encephalitis (an infection that causes brain swelling), severe diarrhoea and related dehydration, ear infections, or severe respiratory infections such as pneumonia (WHO, 2024).

Even with the implementation of routine immunisation, measles continues to circulate globally due to suboptimal vaccination coverage and population immunity gaps. Any community with less than 95% population immunity is at risk for an outbreak. If an outbreak response is not timely and comprehensive, the virus will find its way into more pockets of vulnerable individuals and potentially spread within and beyond the affected countries (WHO, 2019).

The impact on public health will persist until the ongoing outbreaks are controlled, routine immunisation coverage is continuously high (≥95%) and immunity gaps in the population are closed. As long as measles continues to circulate anywhere in the world, no country can be assured of avoiding importation. However, countries can protect their populations through high vaccine coverage achieved primarily through routine immunisation programmes, and where necessary through supplemental immunisation activities designed to ensure that susceptible individuals are vaccinated (WHO, 2019).

Although the measles virus is related to several other viruses that infect animals, humans are the only reservoir for the measles virus. It is therefore theoretically possible that measles could be eradicated from the world (ECDC, no date).

WHO published the Measles and rubella strategic framework in 2020, establishing seven necessary strategic priorities to achieve and sustain the regional measles and rubella elimination goals (WHO, 2020a).

Metrics and numeric limits

Vaccination decreased the estimated measles deaths from 800,062 in 2000 to 107,500 in 2022 (WHO, 2024).

Even though a safe and cost-effective vaccine is available, in 2023, there were an estimated 107,500 measles deaths globally, mostly among unvaccinated or under vaccinated children under the age of 5 years (WHO, 2024).

In 2023, 74% of children received both doses of the measles vaccine, and about 83% of the world's children received one dose of measles vaccine by their first birthday (WHO, 2024). Approximately 22 million infants missed at least one dose of measles vaccine through routine immunisation in 2023 (WHO, 2024).

Key relevant UN convention / multilateral treaty

International Health Regulations (2005), 3rd ed. (WHO, 2016).

Drivers

Any non-immune person (not vaccinated or vaccinated but did not develop immunity) can become infected. Unvaccinated young children and pregnant persons are at highest risk of severe measles complications (WHO, 2024).

Measles is still common, particularly in parts of Africa, the Middle East and Asia. The COVID-19 pandemic led to setbacks in surveillance and immunization efforts. The suspension of immunization services and declines in immunization rates and surveillance across the globe left millions of children vulnerable to preventable diseases like measles (WHO, 2024).

The risk of measles outbreaks is particularly high amongst refugees, who should be vaccinated as soon as possible (WHO, 2024).

Impacts

Complications are most common in children under 5 years and adults over 30. They are more likely in children who are malnourished, especially those without enough vitamin A or with a weak immune system from HIV or other diseases. Measles itself also weakens the immune system and can make the body “forget” how to protect itself against infections, leaving children extremely vulnerable. The virus remains active and contagious in the air or on infected surfaces for up to two hours. For this reason, it is very infectious, and one person infected by measles can infect nine out of 10 of their unvaccinated close contacts. It can be transmitted by an infected person from four days prior to the onset of the rash to four days after the rash erupts (WHO, 2024).

Multi-hazard context

The overwhelming majority of measles deaths occur in countries with low per capita incomes or weak health infrastructures that struggle to reach all children with immunization. Damaged health infrastructure and health services in countries experiencing or recovering from a natural disaster or conflict interrupt routine immunization and overcrowding in residential camps increases the risk of infection. Children with malnutrition or other causes of a weak immune system are at highest risk of death from measles (WHO, 2024).

Risk Management

While there is no specific antiviral treatment for measles, community-wide vaccination is the most effective way to prevent measles. All children should be vaccinated against measles. The vaccine is safe, effective and inexpensive (WHO, 2024).

Children should receive two doses of the vaccine to ensure they are immune. The first dose is usually given at 9 months of age in countries where measles is common and 12–15 months in other countries. A second dose should be given later in childhood, usually at 15–72 months. Children or adults with measles should receive two doses of vitamin A supplements, given 24 hours apart. This restores low vitamin A levels that occur even in well-nourished children. It can help prevent eye damage and blindness. Vitamin A supplements may also reduce the number of measles deaths (WHO, 2024).

Routine measles vaccination combined with mass immunization campaigns in countries with high case rates are crucial for reducing global measles deaths. Two doses of the vaccine are recommended to ensure immunity and prevent outbreaks, as not all children develop immunity from the first dose (WHO, 2024).

The WHO urged all Member States to do the following (WHO, 2019b):

Maintain high measles vaccination coverage (≥95%) with two doses of measles-containing-vaccine, in every district.
Offer vaccination to individuals who do not have proof of vaccination or immunity against measles, and who are at risk of infection and transmission of the virus, such as healthcare workers, people working in tourism and transportation, and international travellers.
Strengthen epidemiological surveillance for cases of ‘fever with rash’ for timely detection of all suspected cases of measles in public and private healthcare facilities.
Ensure that collected blood samples from suspect measles cases are appropriately tested by laboratories within five days.
All countries need to provide a rapid response to imported measles cases to prevent the establishment or re-establishment of endemic transmission.
Recognise complications early and provide comprehensive treatment to reduce the severity of disease and avoid unnecessary deaths.
Administer vitamin A supplementation to all children diagnosed with measles to reduce complications and mortality: two doses of 50,000 IU for a child less than 6 months of age, 100,000 IU for children between 6 and 12 months of age or 200,000 IU for children 12 to 59 months of age, immediately upon diagnosis and on the following day.
Ensure healthcare workers are vaccinated in order to avoid infections acquired in a health-care setting.

The WHO and partners coordinate their support to Member States via their public health response by calling for the following activities: enhancing preparedness for measles outbreak response; strengthening public trust in vaccines; strengthening surveillance, risk assessment and outbreak investigations; improving clinical management of measles cases; implementing outbreak response immunisation activities; and evaluating outbreak response activities (WHO, 2019).

The WHO has established a measles outbreak Incident Management Support system to coordinate its support to affected countries (WHO, 2019).

In 2020, WHO and global stakeholders endorsed the Immunization Agenda 2021–2030. The Agenda aims to achieve the regional targets as a core indicator of impact, positioning measles as a tracer of a health system’s ability to deliver essential childhood vaccines. Based on current trends of measles vaccination coverage and incidence, the WHO Strategic Advisory Group of Experts on Immunization (SAGE concluded that measles elimination is under threat, as the disease resurged in numerous countries that achieved, or were close to achieving, elimination (WHO, no date a). WHO continues to strengthen the Global Measles and Rubella Laboratory Network (GMRLN) to ensure timely diagnosis of measles and track the virus’ spread to assist countries in coordinating targeted vaccination activities and reduce deaths from this vaccine-preventable disease (WHO, 2024; WHO, no date b).

The Measles and rubella strategic framework 2021–2030 (M&RP) is a partnership led by the American Red Cross, United Nations Foundation, Centers for Disease Control and Prevention (CDC), Gavi, the Vaccines Alliance, the Gates Foundation, UNICEF and WHO, to achieve the IA2030 measles and rubella specific targets (WHO, 2020a). Launched in 2001, as the Measles and Rubella Initiative, the revitalized Partnership is committed to ensuring no child dies from measles or is born with congenital rubella syndrome. The Partnership helps countries plan, fund and measure efforts to permanently stop measles and rubella (WHO, 2024).

WHO supports countries to conduct all-hazards strategic risk assessment in the contexts of health emergencies and disasters, which results in the development of a country risk profile. Empowered with the country risk profile, inclusive of a seasonal risk calendar, countries can anticipate potential emergencies before they occur to trigger early alerts and inform early actions (WHO, 2021).

WHO’s Early Warning, Alert and Response System (EWARS) has been designed to improve disease outbreak detection in emergency settings, such as in countries in conflict or following a disaster from natural hazards. It is a simple and cost-effective way to rapidly set up a disease surveillance system. EWARS is deployed during an emergency as an adjunct to the national disease surveillance system. WHO works with Ministries of Health and health sector partners to train local health workers to use the system. After the emergency, EWARS should re-integrate back into the national system (WHO, 2023).

Monitoring

WHO-coordinated surveillance networks have been established for specific vaccine-preventable diseases (VPDs) to provide support to Ministries of Health and surveillance sites. Because some illnesses such as diarrhoea or fever/rash can be caused by several pathogens, global laboratory networks are needed to accurately confirm if the cause is a specific VPD organism, such as rotavirus or measles. In 2017, WHO and UNICEF disseminated the surveillance questionnaire together with the Joint Reporting Form to all 194 WHO Member States. The questionnaire requested information on the current status of surveillance for 28 current and potential future VPDs, attributes of surveillance conducted for each VPD, and details about current measles and rubella surveillance system(s) in each count (WHO, 2020b).