Football fans travelling to and from World Cup matches could trigger a wave of measles outbreaks around the world, experts have warned.

Analysis from Airfinity, a health analytics firm, said travel associated with the tournament could lead to more infections in the three host countries and across the region, posing a particular threat to countries with poor vaccination coverage.

The United States, Canada and Mexico are all experiencing major measles outbreaks, and many matches are set to take place in hotspots like Miami, Houston, Guadalajara and Mexico City, where the tournament got underway yesterday.

In Guadalajara, which will host four matches including Mexico’s second group game against South Korea, some 6,209 cases have been reported so far in 2026, up from nine in 2025.

“All three host nations will begin the tournament amid active measles transmission,” Airfinity’s analysts wrote in a disease surveillance report, published in the build up to the tournament.

The Americas had been declared measles-free in 2016, but the region lost its elimination status in November last year after the disease took hold in Canada. The US has also been experiencing sustained transmission and is set to lose its measles-free status this year.

Measles is one of, if not the most, contagious infectious diseases. The virus spreads through tiny particles released during coughing or sneezing that can hang in the air for hours – people can and do catch measles just by passing through a room where an infected person has been. 

It has a basic reproduction rate of between 12 and 18, meaning a single infected person will spread the virus to 12 to 18 other people on average in an unvaccinated population. By contrast, Ebola, which is currently spreading in the Congo, has a rate ranging from 1.5 to 2.5.

With millions of people set to attend matches across the three host countries in the coming weeks, the potential for spread should be taken seriously, said Adam Finn, Professor of Paediatrics at the University of Bristol.

“In a football stadium – I’m not a great football fan but I’ve been to one or two matches – you walk past a lot of people and a lot of people walk past you, and given that that’s all that it takes, [...] I think it’s a very real possibility that it’s going to be a problem,” he told The Telegraph.

Fans mixing in bars, restaurants and on public transport could also provide the ideal opportunity for measles to spread, he added.

An imported outbreak would not be unprecedented – in 2010, Vancouver experienced a surge in measles cases after the Winter Olympics.

‘There’s measles everywhere now’

While most people think of measles as a disease of childhood with mild symptoms such as the characteristic rash, it can cause a range of serious complications including pneumonia and encephalitis (swelling of the brain) that can lead to loss of hearing or vision, and death.

Measles is often more severe in adults than children – about one in five unvaccinated people who get it in the US require hospital treatment, according to the US Centers for Disease Control and Prevention (CDC).

It is a preventable disease. The first measles vaccine was licensed for use in 1963 and the current two-dose measles, mumps and rubella (MMR) jab is highly effective. But childhood vaccination rates have fallen in recent years, particularly during and after the pandemic, allowing the virus to make a resurgence.

In Canada, for example, the percentage of children aged seven or under who have received both doses of the measles vaccine dropped from 95 per cent in 2014 to 79 per cent in 2024, while coverage has also fallen across the border in the US.

In Mexico, childhood vaccination rates have fallen dramatically in recent years as a result of disruption to national immunisation programmes, with only about 69 per cent of children receiving both doses of the MMR jab. Significant immunity gaps also exist among adults aged 20 to 49.

Two-dose measles vaccination rates have fallen below the World Health Organization’s 95 per cent target among many countries competing in the tournament – among them some of the favorites to win it.

For example, Argentina might be ranked number one in the world by FIFA, but if you were to rank all of the teams taking part by immunisation levels, Los Albicelestes would actually rank last (the country’s two-dose measles rate was just 46 per cent in 2024, worse even than the Democratic Republic of Congo or Haiti).

All told, only 12 of the 48 countries competing in the tournament are currently hitting the WHO’s 95 per cent vaccination target. But even in these countries, pockets of under-immunised people could provide fertile ground for outbreaks. 

Another factor that may help the virus to spread across borders is its incubation period, with the first symptoms typically appearing around two weeks after infection. This, experts warn, may help the virus move around undetected.

“Infected travellers could pass through major transit and fan hubs before detection,” Airfinity’s analysts wrote.

Prof Finn said: “The incubation period is 10 to 14 days, and the infectious period begins before there are any symptoms – before you develop fever or rash or any of the other features that might give you the clue that you’ve got measles, you will be infecting other people.”

But the worry isn’t just that fans travelling in the host countries could pick up measles and bring it home with them – fans bringing cases in with them and infecting under-immunised communities is also a concern.

“There’s measles everywhere now,” said Prof Finn, adding that Europe has emerged as the global “engine” for the virus.

“We’re seeing more cases in Europe than in any other continent, at least in terms of the incidence – the number of cases per 100,000 people per year – and it’s really going up,” he said.

“There are very few countries now where measles is still apparently under control. Portugal, for example, is one where they’ve maintained high coverage in the vaccine program, but many other countries, including the United Kingdom and France and Italy, are seeing a lot of cases.”

“We need to be equally worried about the idea of us taking measles to them as about them giving measles to us.”

The latest UK Health Security Agency (UKHSA) measles data is a case in point. Some 736 cases have now been recorded in England since January 1, compared to 959 cases for the whole of 2025. The disease has already claimed the lives of two children.

James Murray, the Health Secretary, said: “My thoughts are with the families who have suffered such unimaginable loss. These deaths are a heartbreaking reminder that measles is not a harmless childhood illness.”

Experts say that making sure you are fully vaccinated is the best defence against measles at the World Cup, and regional and local health authorities are urging fans to get the MMR jab.

The Pan American Health Organization (PAHO), the WHO’s regional office covering the Americas, earlier this month recommended countries to advise any travellers who cannot provide proof of vaccination or immunity be given a dose of the MMR jab two weeks before travel.

PAHO also called on countries to strengthen surveillance in high-risk areas including border regions, airports and ports.

Significant effort is also going into shoring up surveillance protocols within the host countries.

Earlier this year The Telegraph reported on the establishment of a new temporary surveillance hub – the Health Security Operations Centre – being set up by experts from Georgetown University in Washington, DC, to track infectious disease threats including measles.

Its aim is to track cases and provide warnings and support to the health authorities to prevent local outbreaks from spiralling out of control.

But Tim Manning, a Research Professor at the Center for Global Health Science and Security at Georgetown University, said the information gathered by the hub could prove useful for the rest of the world, too.

“A lot of these populations that will be [going to games] will then then be moving back around the world,” he told The Telegraph. “So providing information on what’s happening here as people return back home to other countries and other parts of the world can be helpful as well.”

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