Measles is one of the most contagious diseases humans have ever faced. An ancient disease, it was described as early as the 9th century by Persian physician and scholar Abū Bakr Muhammad Zakariyyā Rāzī (also known by the Europeanized name Rhazes). 

It became more widespread as global exploration increased in the 16th century. In 1757, Scottish doctor Francis Home discovered that measles was caused by a pathogen: he transmitted the disease to healthy individuals using the blood of infected patients and demonstrated that it was caused by an infectious agent.

Regions of the world without previous exposure to the measles virus were particularly vulnerable: outbreaks of the virus took devastating effect in isolated communities such as the Faroe Islands in 1846, Hawai`i in 1848, Fiji in 1875 and Rotuma in 1911.

Before the advent of vaccination, measles had long been endemic around the world – and it remains a worldwide epidemic disease. In developed countries, advances in the health of communities  – including better nutrition – meant mortality rates had dropped by the twentieth century. 

The availability of antibiotics, while powerless against the virus itself, could also help fight complications such as bacterial pneumonia. Yet common complications such as ear infections, croup, diarrhoea and pneumonia caused thousands of hospitalizations annually, and encephalitis, a more serious complication involving swelling of the brain, could result in brain damage, loss of hearing or vision, and death. 

Globally, mortality rates remained high, with approximately 30 million cases and over 2 million deaths occurring each year.

In 1954, a measles outbreak at a boarding school just outside Boston, Massachusetts provided an opportunity for doctors at Boston Children’s Hospital to try and isolate the measles virus, taking throat swabs and blood samples from infected students. 

The culture that Thomas Peebles, MD obtained from 11-year-old schoolboy David Edmonston successfully led to the virus’s cultivation and enabled doctors to create the first vaccine against measles.

John Franklin Enders, Peebles’s boss, often called ‘the father of modern vaccines’, developed the measles vaccine from the ‘Edmonston-B’ strain, named after David and used as the basis for most live-attenuated vaccines to this day. 

Enders and his team tested their measles vaccine on small groups of children from 1958 to 1960, before beginning trials on thousands of children in New York City and Nigeria.  In 1961 it was hailed as 100% effective and the first measles vaccine was licensed for public use in 1963.

Individual countries introduced mass vaccination programmes against measles at the national level from the 1960s on, and the first internationally focused measles immunization programmes took place in Africa from 1966.

WHO worked with the governments of over 20 newly independent and decolonizing countries in western and central Africa, alongside the United States Agency for International Development (USAID) and Centres for Disease Control (CDC), to administer vaccinations with the joint aim of controlling measles and eradicating smallpox. 

Despite challenges such as the difficulty of maintaining the cold chain when transporting and storing the heat-sensitive vaccine, these campaigns provided evidence that vaccination was effective against measles, and by May 1967 The Gambia became the first country in the world in which transmission of the virus was interrupted.

An improved version of the measles vaccine was created in 1968 when Dr Maurice Hilleman, a pioneer in vaccine development, passed the virus through chick embryo cells 40 times to weaken it, producing a vaccine that did not cause such severe side effects. 

This weaker version, known as the Edmonston-Enders strain, was developed into some of the strains still used in measles vaccines today.

In 1971 Hilleman combined the recently developed vaccines against measles, mumps and rubella into the MMR vaccine, administered as a single shot, with one booster dose following – and in 2005, the varicella vaccine was added, to make the combined MMRV vaccine. 

Standalone measles vaccines remain available in many countries.

In 1974, measles was among the first diseases targeted by the World Health Organization (WHO) when it established the Expanded Programme on Immunization (EPI, now the Essential Programme on Immunization) to develop and expand immunization programmes throughout the world. 

Widespread childhood vaccination against measles has drastically reduced disease rates worldwide. WHO now recommends vaccination at 9 months for babies in areas where measles is common, and at 12–15 months for those in other areas. 

A second dose is recommended for all children, essential to protect the approximately 15% of children who don’t develop protective immunity after their first dose.

Measles elimination efforts in the Americas Region started in 1991 and all those 9-15 years of age in the region were vaccinated with an additional dose of measles vaccine. The strategies for elimination in use today were first developed and implemented in the Region of the Americas.

A minor setback for the success of the measles vaccination programme occurred in 1998, when a fraudulent research paper was published in ‘The Lancet’, asserting a link between the MMR vaccine and autism without any robust scientific evidence. 

The influence of this paper, along with systemic misinformation by anti-vaccination groups in high-income countries, resulted in a drop in vaccination rates, below the level required for community protection, which caused a resurgence in measles cases in  England and Wales, as well as parts of the USA and Canada.

In 2010 the British General Medical Council ruled that the study’s lead author engaged in misconduct. The paper was formally retracted by ‘The Lancet’, and its author was banned from practising medicine.

Because measles has such a high infectivity rate, the threshold for community protection is also very high, requiring at least 95% immunity among the population to prevent epidemics. The failure to maintain very high rates of immunization can result in outbreaks when the disease is reintroduced. 

In addition to the suffering caused by measles, containing outbreaks is costly and detracts from other health care services. Measles deaths continue to occur in many countries, especially those with gaps in their immunization programmes.

For example, in the Democratic Republic of the Congo 2299 people died during the Ebola epidemic of 2018–2020, compared with 7,800 deaths from measles during an outbreak in the same time period.

The region of the Americas was declared free of endemic measles in 2016 by an independent body of experts, becoming the first WHO region to achieve this distinction of having eliminated measles. 

But this status was lost two years later due to a measles outbreak, initiated by a social and political crisis in one country where there were gaps in vaccination coverage and delays in implementing a rapid response. The virus spread to neighboring countries where it was successfully controlled.

To address these issues, the Pan American Health Organization (PAHO, the WHO Regional Office for the Americas), has trained countries in rapid response to avoid measles and rubella virus spreading, improved surveillance, and launched renewed high-quality follow up vaccination campaigns.

Between 2000 and 2020, measles vaccination prevented an estimated 31.7 million deaths worldwide.

But even though a safe and cost-effective vaccine is available, global measles deaths continued to climb prior to the COVID-19 pandemic. In 2019 there were over 207 000 measles deaths globally, and the highest number of reported cases in 23 years.

Watch this video and learn the five things to know about measles.