Professor Christina Pagel (UCL Mathematics) warns that the US Secretary of Health and Human Services’ efforts to undermine vaccines spreading around the world.
Vaccines are one of the greatest public health success stories of all time. Over the past 50 years, they’ve saved an estimated 154 million lives. But in the US, both access to vaccines and public trust in them are being systematically undermined - not by conspiracy theorists online, but from within the highest levels of government. "
In January 2025, Robert F. Kennedy Jr - long associated with vaccine misinformation - was confirmed as US health secretary. Despite being pressed during his Senate confirmation hearings , Kennedy insisted he was not anti-vaccine and pledged to maintain scientific standards.
Seven months later, his actions tell a different story.
Kennedy has launched a sweeping assault on the US vaccine infrastructure: gutting oversight committees, sowing doubt about settled science, politicising ingredient safety, limiting access to vaccines and halting funding for research. His strategy doesn’t involve outright bans. But the cumulative effect may prove just as damaging.
In the US, the Advisory Committee on Immunization Practices (ACIP) plays a central role in vaccine policy, offering evidence-based recommendations on schedules. Until recently, its members were respected experts in immunology, epidemiology and infectious disease - all vetted, conflict-checked and publicly accountable.
In May 2025, Kennedy overrode ACIP’s recommendation on COVID-19 vaccination for pregnant women and young children. The following month, he disbanded the 17-member committee , citing alleged conflicts of interest. In their place, Kennedy appointed a smaller panel that included people with well-documented anti-vaccine views.
This broke decades of precedent. For the first time, ACIP’s membership was handpicked by the health secretary without standard vetting, training or safeguards to ensure independence.
In July, the ousted ACIP members published a commentary in the New England Journal of Medicine, warning the recommendation process was facing "seismic disruption". In August, Kennedy banned respected scientific societies from advising ACIP, claiming they were too biased. This removed yet another check on the panel’s independence.
Meanwhile, Kennedy has reopened long-closed debates. He has called for "reassessment" of the childhood vaccine schedule , standard vaccine ingredients , and reportedly even the thoroughly debunked claim that the MMR vaccine is linked to autism. The latter has been refuted by multiple peer-reviewed studies, including a meta-analysis involving over 1.2 million children.
At ACIP’s first meeting under new leadership, Kennedy’s panel reviewed thimerosal, a mercury-based preservative used in some flu vaccines. CDC scientists were scheduled to present their evidence but were dropped from the agenda. Instead, the only evidence came from Lyn Redwood, a vaccine critic and co-founder of the World Mercury Project , an initiative that preceded Kennedy’s own Children’s Health Defense group.
Her presentation appeared to include at least one non-existent study , yet ACIP went on to ban thimerosal from flu shots - a decision Kennedy later extended to all’US vaccines.
Though thimerosal was already used in very few vaccines, the way it was removed - based on flawed evidence and limited expert input - sets a dangerous precedent.
Kennedy has also criticised aluminium hydroxide, used in many vaccines to boost the immune response. His review article contradicts a large body of peer-reviewed evidence that supports its safety. Aluminium salts are found in vaccines against hepatitis A and B, meningococcal disease and tetanus.
Restricting access and innovation
The ripple effects of Kennedy’s changes go beyond oversight. In July, ACIP announced it would review recommendations for childhood vaccines, hepatitis B at birth, and the MMRV combination vaccine -- a single shot that protects against measles, mumps, rubella, and varicella (chickenpox).
These guidelines help determine what vaccines are covered by public insurers like Medicaid. Weakening them could make vaccines unaffordable for low-income families.
Kennedy has also targeted the Vaccine Compensation Program , which provides payouts for rare adverse effects while protecting vaccine supply from litigation. He is considering expanding eligibility to include autism, despite consensus refuting any link, and may allow more lawsuits. These changes could deter pharmaceutical companies from offering vaccines in the US.
Kennedy has insisted that all new vaccines must undergo new placebo-controlled trials , ignoring the fact that new vaccines already follow this standard. Only modified versions of approved vaccines - like annual flu shots - are currently exempt, for ethical reasons.
If Kennedy bans widely used ingredients like aluminium salts, companies may be forced to reformulate vaccines - triggering unnecessary full clinical trials (the multi-phase process typically required for entirely new vaccines) and delaying access to boosters.
In May, vaccine manufacturer Moderna withdrew its application for a combined COVID-flu vaccine, citing regulatory difficulties. Days later, Kennedy’s department cancelled US$700 million (£550 million) in funding for a Moderna bird flu vaccine, followed by cuts to HIV vaccine research and mRNA platforms for cancer prevention.
Other countries may continue vaccine research, but the US’s retreat leaves a major gap.
Destabilising global trust
Perhaps most troubling is the messaging. Kennedy has repeatedly questioned the need for childhood vaccines , spread misinformation , inflated the risks and downplayed the threat of measles.
He has also attacked medical journals as corrupt and threatened to bar government scientists from publishing in respected outlets such as The Lancet and The New England Journal of Medicine - two of the world’s most prestigious peer-reviewed journals. Instead, he has proposed state-run alternatives. His own review on Aluminium Hydroxide was published in a non-peer-reviewed outlet.
In just a few months as health secretary, Kennedy has reshaped vaccine policy and public trust in the US. He has repeatedly claimed that the scientific and medical establishment is corrupt and that consensus cannot be trusted. This rhetoric is especially dangerous at a time when vaccine uptake is already low and falling.
But the consequences don’t stop at national borders. When coverage drops in one country, the risk of disease outbreaks increases globally, as seen in the recent measles outbreak in Canada.
Kennedy has shown both determination and ingenuity in undermining vaccine science, often through methods that are complex, obscure, or hard to explain publicly. Without issuing a single ban, he has weakened the foundations of vaccine availability and trust in the US.
In the 19th century, the average life expectancy in the US was around 40 years. Many children died of infections that are now preventable. In an age when the deadly realities of diseases like measles have faded from memory, it’s chilling to consider the possibility of returning to a pre-vaccine era.
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