Public trust and evidence: decisions on vaccines must be anchored in science

US President Donald Trump recently signed an executive order aimed at reducing the number of routine childhood vaccinations in the United States and replacing combined vaccines for measles, mumps and rubella (MMR) with separate single-antigen vaccines for the three conditions.¹

While the European Medicines Agency (EMA) does not usually comment on vaccination policy decisions taken outside the European Union (EU) or European Economic Area (EEA), this recent development in the US will undoubtedly influence public debate in Europe and elsewhere in the world. In an increasingly interconnected world, it is no surprise that decisions on vaccines in one jurisdiction can affect public attitudes in others.

EMA considers that maintaining public confidence about vaccines requires not only robust scientific evidence, but also transparent and consistent communication about how and why recommendations for vaccines are made. Therefore, when there is a disconnect between science and decisions taken by public authorities, there is a duty to restate the scientific evidence and the public health reasoning that are behind the current recommendations and what such ungrounded changes could mean for the return of infectious diseases and the damage they bring to global public health.

Unfortunately, the US bid to replace the combined MMR vaccine with separate single-antigen vaccines has not been based on any new or emerging data. It is, however, likely to raise questions, even doubts, about the combined vaccine among the public in other jurisdictions.

The reality is that combined measles, mumps and rubella (MMR) vaccines have been used worldwide for decades to protect children against measles, mumps and rubella and their safety profile is well-established. To date, there is no scientific evidence that administering single-antigen measles, mumps and rubella vaccines separately offers any advantage over the combined MMR vaccine in terms of safety, effectiveness or health outcomes for children.^2,3

What we do know is that introducing barriers to vaccination does not lead to better public health protection. Replacing a single MMR vaccination visit with separate single-pathogen vaccinations over a longer period would delay protection against one or more of these diseases, extending the period during which children are at risk of infection. Most importantly, additional appointments will increase the likelihood of missed or delayed vaccinations, creating practical challenges for families and healthcare systems alike, leading to decreased vaccine coverage.^4,5

The consideration to provide separate single-antigen vaccines runs counter to decades of experience showing that combination vaccines can simplify immunisation schedules and support timely vaccine uptake. Science agrees that we need to be thinking about strategies that would make vaccination easier, not more complicated, by combining different vaccines into a single timely administration.⁶

The World Health Organization (WHO) estimates that immunisation prevents millions of deaths annually.⁷ Sustaining these achievements requires confidence in the institutions and processes responsible for evaluating vaccines and developing recommendations.

Although vaccination recommendations vary between countries, reflecting differences in local epidemiology, they share a common objective: ensuring that children are protected against serious infectious diseases at the ages when vaccination provides the greatest benefit. Vaccine recommendations are, and must continue to be, anchored in science to achieve the best outcomes and maintain public trust. Indeed, public trust is itself essential to achieve the best outcomes, as mistrust and vaccine hesitancy put at risk the decades of progress made in preventing serious infectious diseases, as we see with the recent resurgence of measles outbreaks in the US and EU.^8,9

Maintaining public trust requires transparent communication about the reasoning behind recommendations. What scientific evidence on vaccines is available? How are they evaluated? Why are particular approaches adopted? At a time when vaccine-preventable diseases continue to pose a threat, we must rise to the challenge of sustaining confidence in the scientific processes and in the institutions that regulate vaccines and develop vaccination policies.

In April 2026, EMA established its Advisory Group on Vaccine Confidence to provide independent expertise on the social, behavioural and communication factors that influence public trust in vaccines.¹⁰ The establishment of this advisory group reflects an important reality: that public confidence is shaped not only by the evidence supporting vaccines, but also by how that evidence is communicated and interpreted. And to counter societal mistrust fuelled by misinformation, we should all ensure that we communicate–clearly and transparently–how decisions on approval and recommendation of use of vaccines that protect public health are anchored in science.

Declaration of interests

The author declares he has no conflicts of interests.