That is what is happening today with measles. The virus is circulating in the United States but also, and more surprisingly, in Europe.
In the space of a year, the European Centre for Disease Prevention and Control (ECDC) has recorded 2,339 reported cases in Europe. We are not yet at pandemic levels – far from it – but behind this figure lies a striking fact : nearly three in four infections involved unvaccinated people.
However, to stop the spread of measles in the long term, vaccination coverage must reach 95 per cent of the population with two doses. In 2023, only four countries in the European Free Trade Area met this threshold for the second dose. Spoiler alert : Belgium is not one of them… Its coverage stands at 96 per cent for the first dose but only 82 per cent for the second.
There are many reasons for this resurgence of measles: access to healthcare that can sometimes be difficult, particularly for vulnerable groups; and booster vaccinations that are not necessarily up to date. Missed opportunities. And, in some cases, a deliberate refusal to be vaccinated.
But there is another factor that exacerbates all these vulnerabilities : disinformation.
There’s no need to convince millions of Europeans that a vaccine is dangerous. All you need to do is sow the seeds of doubt. Is it really necessary ? Are the authorities telling us the whole truth? Is a doctor more credible than a viral social media post ?
What’s more, doubt spreads very easily. During the Covid pandemic, anti-vaccine communities flourished on social media. A study focusing on the Facebook group “Antivax Portugal” analysed 440 posts from 2020 : nearly half were classified as conspiracy theories, and some could influence users who were still hesitant about vaccination.
Five years after the pandemic, the European Health Observatory noted that misinformation was still widespread. Targeting the most vulnerable, namely “populations with limited health literacy or pre-existing mistrust of institutions are disproportionately affected, exacerbating pre-existing health inequalities”.
A study published in 2025 in the journal *Human Vaccines & Immunotherapies* drives the point home. “The mistrust fuelled during the Covid-19 pandemic has spread to routine childhood vaccinations,” the researchers explain, “raising the alarming possibility of a resurgence of diseases such as measles, diphtheria and polio – diseases that have been widely regarded as under control for decades.”
Disinformation does not need to create mistrust from scratch; it can simply rub salt into existing wounds. And that is precisely where the issue of interference becomes interesting.
In several countries in Central and Eastern Europe, the authorities have condemned the circulation of anti-vaccine narratives attributed to campaigns originating in Russia. In Bulgaria, during a measles outbreak in March 2026, the then Health Minister Mihail Okoloyski publicly identified the fight against vaccine disinformation as a priority: “There are many measures that could be implemented and are currently being implemented. The most important is to combat disinformation concerning vaccines.”
At the same time, the Bulgarian National Network of Health Mediators posted on Facebook that anti-vaccine profiles and groups had become more active on social media and were attempting to undermine the health authorities’ efforts to contain the outbreak.
But beware of jumping to conclusions. Behind every hesitant parent, every dubious social media post or every anti-vaccine movement, there isn’t necessarily an agent from Moscow. False information can be shared in good faith and, gradually, an imported narrative becomes entirely local. This is particularly evident in the American anti-vaccine movement.
In 2023, the European Digital Media Observatory (EDMO) documented the expansion across Europe of Children’s Health Defense, the organisation founded by Robert Kennedy Jr. In particular, the organisation had established a legal entity in Belgium and organised events aimed at disseminating its narratives on vaccines and health across Europe.
Brussels is therefore not merely the seat of the European institutions. It is also a gateway for political and activist movements from elsewhere that wish to influence the European debate. And this influence can ultimately reach the parliaments.
In October 2025, the "Make Europe Healthy Again" movement, directly inspired by the American populist slogan "Make America Healthy Again", was launched in the European Parliament with the support of the far-right group Les Patriotes pour l’Europe.
"In Western European countries, populist parties, most often in opposition to the government, have used the pandemic and Covid-19 vaccination to gain political capital, according to a 2025 study published in the scientific journal Vaccine.
A child accompanied by a parent goes to the vaccination centre at Parque das Nações in Lisbon on 18 December 2021 to receive a dose of the Covid-19 vaccine, as Portugal launched its vaccination campaign for children aged 5 to 11. PATRICIA DE MELO MOREIRA / AFP
In fact, in Austria, far-right and populist parties have rallied round the issue of anti-vaccination. The leader of the far-right FPÖ party, Herbert Kickl, has described himself as a “vaccine sceptic”, whilst in August, MEP Gerald Hauser called for an investigation into deaths linked to vaccines, particularly Covid-19 vaccines.
So we have a narrative that originates or gains traction abroad, is then imported into Europe, and is subsequently taken up by European far-right activists, who inject it into the political debate; ultimately, this will help to change the way public officials talk about vaccination and health.
It is not necessarily a centralised operation, nor is it necessarily illegal, but it is certainly a form of transnational influence, and that is precisely what makes the phenomenon so difficult to combat.
In Belgium, the anti-vaccination movement remains relatively marginal, but that does not mean the country is immune to scepticism. In 2024, the country experienced its largest measles outbreak since 2011, with 526 cases recorded. Unvaccinated children were particularly affected.
Even in regions where the population largely adheres to vaccination schedules, misinformation has sown doubt.
To counter this misinformation, the European Medicines Agency announced that it would set up an advisory group tasked with investigating and formulating recommendations on vaccine hesitancy, with the aim of boosting confidence in vaccines.
Because the problem is not simply a matter of correcting fake news. A health authority may publish 10 charts demonstrating that a piece of information is false, but if the public does not trust it, those charts will have no effect. The battle is therefore as much a battle of facts as it is a battle of trust
The JITSUVAX project, funded by the EU, has in fact been working on a different approach. The researchers have organised interviews with patients who refuse to be vaccinated. The aim is, first and foremost, to understand these patients’ concerns before addressing any misconceptions.
The trials carried out as part of the project have shown that this approach can boost the confidence of healthcare professionals and their ability to respond to anti-vaccine arguments. It now needs to be rolled out across the European Union.
It’s less spectacular than a viral video, but when it comes to public health, what’s spectacular isn’t necessarily the most effective.
An article written by Olivier Hanrion (RTBF), initially published on 25 September 2026, 16:54 (CEST)