Measles 'a global threat': What is it and why are cases soaring now?

This article was first published in May 2022 and updated in November 2022.

Measles cases are soaring as children miss crucial vaccinations.

In November, the World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC) declared measles "an imminent threat in every region of the world".

Nearly 40 million children missed a measles vaccine dose in 2021, due to COVID-19 disruption. Measles killed more than 120,000 people and there were an estimated 9 million cases worldwide, with large outbreaks in 22 countries.

WHO Director-General Dr Tedros Adhanom Ghebreyesus said: “The paradox of the pandemic is that while vaccines against COVID-19 were developed in record time and deployed in the largest vaccination campaign in history, routine immunization programmes were badly disrupted, and millions of kids missed out on life-saving vaccinations against deadly diseases like measles.

"Getting immunization programmes back on track is absolutely critical. Behind every statistic in this report is a child at risk of a preventable disease.”

In the first two months of 2022, measles cases jumped almost 80% compared to the same time last year, data from UNICEF and the WHO showed.

So what is going on and just how serious is this disease?

Measles is a highly contagious disease. In 2018, measles killed more than 140,000 people, according to the WHO. Most of these were children younger than five years old. In developing countries, particularly in parts of Africa and Asia, measles is still common.

Measles is caused by a virus that infects the respiratory tract. This then spreads through the body. Symptoms include a high fever and rash. Measles can lead to serious complications including blindness, encephalitis – an infection that causes brain swelling – and severe respiratory infections like pneumonia. It’s these complications that lead to most deaths. Young children who are unvaccinated and poorly nourished are most at risk from measles.

Measles is spread through the air – by coughing and sneezing – and by direct contact with infected secretions from the nose or throat.

A measles vaccine was introduced in 1963 and led to widespread vaccination. Before this, measles killed about 2.6 million people a year, the WHO says, and there were measles epidemics roughly every two to three years.

Death rates were higher in poorer countries, but measles also infected around 500,000 Americans a year in the mid-1950s, killing around 10% of them. By 2000, the United Sates was declared measles-free.

Between 2000 and 2018, more than 23 million deaths globally have been prevented by measles vaccination, according to the WHO. This makes the measles vaccine “one of the best buys in public health,” it adds.

In January and February 2022, there were 17,338 measles cases reported worldwide, UNICEF and the WHO say. This is 79% higher than the 9,665 cases reported over the same period in 2021.

Somalia, Yemen, Nigeria, Afghanistan and Ethiopia are the top five countries with the biggest measles outbreaks in the past year.

The COVID-19 pandemic led to resources being diverted from routine immunization, UNICEF and the WHO say. Not enough availability of the measles vaccine is the main reason for every measles outbreak, they add.

Now there is a risk of larger measles outbreaks. Factors fuelling this include the relaxation of COVID-19 restrictions and the displacement of millions of people from crises and conflict, including the war in Ukraine.

Polio, a highly infectious disease that can lead to paralysis, is another disease in danger of reemerging, due to the pandemic slowing vaccination efforts. Across North and South America and its associated islands – the region collectively known as the Americas – the vaccination rate for polio in 2020 was 82%. This is the lowest since 1994, when the Americas was certified free of polio, according to The Pan American Health Organization.

Earlier this year, Malawi in south-eastern Africa also reported its first clinically confirmed case of wild polio since 1992.

In 43 countries, 57 vaccination campaigns for preventable diseases were still postponed in April 2022. This includes 19 for measles, putting 73 million children at risk.

UNICEF and the WHO want to see these postponed campaigns restored. Their call is supported by partners including Gavi, the Vaccine Alliance, the Measles & Rubella Initiative and the Bill & Melinda Gates Foundation.

In November, the CDC and WHO urged coordinated and collaborative action from all partners at global, regional, national and local levels to prioritize efforts to find and immunize all unprotected children, including those who were missed during the past two years.

Other steps needed to strengthen immunization programmes include helping health workers and community leaders explain the importance of vaccinations and making sure that COVID-19 vaccination is independently financed, so it’s not paid for out of other vaccination budgets.

As part of their COVID-19 recovery efforts, countries should also develop plans to prevent and respond to outbreaks of vaccine-preventable diseases, says the WHO.