The United States is edging closer to losing its measles elimination status as cases surge, a development that carries direct implications for Europe, where vaccination coverage in several countries remains below the level required to stop sustained transmission.
More than 4,500 measles cases have been reported in the US this year—roughly double the total for all of last year. A forecast in JAMA warns that if vaccination rates do not improve, measles could become endemic again in the US, potentially causing 851,300 cases, over 170,000 hospitalisations, and 2,550 deaths over the next quarter-century.
The transatlantic outbreak is a reminder that viruses do not respect borders. Kitty Mohan, vice-president of the Standing Committee of European Doctors (CPME) and its rapporteur on vaccination, told Euronews: “Due to international travel routes and the ease and speed at which people move across borders, combined with the infectiousness of measles before the rash starts, people can travel quite far whilst infectious and so the disease can spread rapidly.”
Measles is among the most contagious infectious diseases known. An infected person can transmit the virus for about four days before the tell-tale rash appears, meaning they may board a flight from New York to Paris or Berlin without knowing they are ill. Mohan noted that “15 mins face to face with someone who is infectious will mean you are likely to get measles.”
Europe's immunity gap
The US is not alone in struggling with measles. The largest outbreaks currently are in Bangladesh (over 65,430 cases), Indonesia (46,578), and Guatemala (31,222). But the risk to Europe depends on local immunity levels. The European Centre for Disease Prevention and Control (ECDC) told Euronews: “Whether an imported case leads to further transmission in Europe depends primarily on immunity levels in the affected community in Europe and whether the virus reaches groups with low vaccination coverage.”
Across the European Union and the wider European Economic Area, vaccination coverage stands at 92% for the first dose and 88% for the second dose. The ECDC describes this as “strong population protection,” but it falls short of the recommended 95% two-dose coverage needed at national and local levels to prevent sustained transmission and achieve measles elimination. National averages can also mask significant local gaps.
“Most measles cases occur in unvaccinated people,” the ECDC said, urging countries to close immunity gaps, ensure both doses are given on time, offer catch-up vaccination to adolescents and adults, and maintain robust surveillance and outbreak-response systems.
The consequences extend beyond those who choose not to vaccinate. Infants too young for the vaccine, people with medical contraindications, and those with weakened immune systems rely on high levels of immunity in the wider population. “Herd immunity or maintaining vaccination rates above a threshold would protect these groups—so lower rates make them more susceptible to disease,” Mohan explained.
Pockets of low coverage
The problem is not confined to countries with low national vaccination rates. Clusters of unvaccinated or under-vaccinated people can emerge within otherwise well-protected populations, creating local conditions where outbreaks can take hold. These gaps may stem from difficulties accessing vaccination services, limited information, or vaccine hesitancy.
“There are traditional risk groups—such as traveller communities and some religious groups who historically have been reluctant to vaccinate,” said Mohan.
However, the ECDC stressed that “the presence of a group of unvaccinated people does not automatically mean that a large outbreak will spread across the wider population.” It pointed to the Urkult festival in northern Sweden, held from 30 July to 2 August this year, where an outbreak affected 28 people, mostly unvaccinated children and adolescents, with 12 secondary cases—but it did not lead to sustained spread.
Johanna Rubin, Acting Head of the Vaccination Unit at Sweden’s public health agency, said: “The fact that there were relatively few secondary cases among those exposed at the festival is due to the high level of immunity within the population, a result of strong participation in the childhood vaccination program.” The ECDC added: “This once again highlights the importance of high community-level protection.”
For now, the ECDC’s latest assessment keeps the overall risk for Europeans moderate for infants under 12 months, children aged one to five, and immunocompromised people. For older unvaccinated children and adults, the risk ranges from low to moderate. Those with immunity from vaccination or previous infection are considered at low risk.
ECDC surveillance data show fewer reported measles cases in 2026 than in 2025, though 2026 figures are preliminary and should be interpreted with caution. Measles remains endemic in twelve European countries: Bosnia and Herzegovina, France, Georgia, Germany, Italy, Kazakhstan, Kyrgyzstan, Poland, Romania, Russia, Türkiye, and Ukraine. Romania reported the most cases—30,692 in 2024, up from 3,371 in 2023. Six other countries—Armenia, Austria, Azerbaijan, Spain, the United Kingdom, and Uzbekistan—have re-established endemic transmission based on 2024 case numbers.
The US experience is a stark warning. As international travel rebounds, Europe’s vaccination gaps could turn a single imported case into a local outbreak. The solution, as the ECDC and medical experts reiterate, is to close the immunity gaps now—before the next traveller arrives.
