Gavi, the Vaccine Alliance has been one of the most successful global health partnerships in modern history, helping immunize more than a billion children and preventing an estimated 17 million deaths since its founding in 2000.
The United States has been one of its biggest supporters. It is not charity; that support has been an important part of American health security and global leadership. By helping expand vaccine access in low- and middle-income countries, Gavi reduces the risk that outbreaks of polio, influenza, and other vaccine-preventable infectious diseases will spread unchecked and ultimately reach US shores.
Much like putting out a spark before it ignites a wildfire, preventing outbreaks at their source is far more effective—and less costly—than responding once they become global emergencies. At the same time, US engagement with Gavi reinforces American leadership in global health, strengthens diplomatic relationships, and signals a commitment to evidence-based policy that has long underpinned US credibility abroad.
Ideology over evidence, at home and abroad
Unfortunately, Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. halted funding for Gavi in early 2025, alleging that the organization had ignored vaccine safety science. Now, reports indicate that the United States is pressuring Gavi to phase out vaccines containing the preservative thimerosal—long a target of anti-vaccine advocates and conspiracy theorists—as a condition of restoring US funding.
This is not an evidence-based intervention; it is an ideological one—and part of a pattern. Like recent changes to the childhood vaccine schedule and other HHS actions, it was guided by politics and ideology, not facts—to the detriment of our health and, ultimately, to the detriment of Americans’ ability to trust their health agencies.
The thimerosal ultimatum was well-worn territory for the health secretary. In 2005, Kennedy wrote an article called “Deadly Immunity,” that appeared in Rolling Stone and on Salon.com, connecting thimerosal to autism. Both publications later pulled the piece, because the data it relied on were inaccurate or taken out of context.In 2014, he published a book about thimerosal. It received similarly scathing reviews from experts for misstating data and exaggerating risks.
The conclusions in these pieces and Kennedy’s conditioning of Gavi funding are unsupported by fact. For decades, the Centers for Disease Control and Prevention (CDC) has been unequivocal: thimerosal is not linked to autism or other neurodevelopmental disorders. Large epidemiologic studies in the United States and other countries have looked and consistently found no association. The Institute of Medicine (now the National Academy of Medicine) reviewed more than 200 studies and reached the same conclusion.
Gavi continues to work to secure US government funding, but if it fails, its chief executive said it would result in 1.3 million children dying from vaccine-preventable illnesses.
When thimerosal was removed from nearly all routine childhood vaccines in the United States more than two decades ago—a precautionary step taken to promote confidence, not a response to demonstrated harm—rates of autism continued to rise, further undercutting claims of causation.
CDC’s vaccine safety pages continue to describe the body of evidence. They explain the difference between the preservative ethylmercury—added to vaccines in multidose vials to prevent contamination —which is cleared quickly from the body, and methylmercury (not a vaccine ingredient), which accumulates and is known to be harmful at high exposures. The CDC summarizes decades of research and addresses common fears.
But when the CDC sought to update the evidence last year in advance of an Advisory Committee on Immunization Practices (ACIP) meeting where thimerosal was discussed, HHS pulled the document. (We’ve posted it here.) The evidence in it contradicted the content of a presentation being made at ACIP by an anti-vaccine activist who was brought on board at the CDC.
Gavi continues to work to secure US government funding, but if it fails, its chief executive said it would result in 1.3 million children dying from vaccine-preventable illnesses.
If trust is the goal, sound data can’t be ignored
National Institutes of Health Director Jay Bhattacharya, MD, PhD, recently told the New York Times that he wants to reform “public health authorities so that they become worthy of trust.” Bhattacharya said 75% of the public trusting in federal health agencies—a not uncommon reading prior to the pandemic—isn’t enough. It should be 100%.
Trust cannot be restored through words alone. And trust cannot be rebuilt while senior federal health officials repeatedly misstate evidence, fail to answer direct questions, change policy without open discussion, and quietly erase inconvenient facts from government websites.
Not surprisingly, and contrary to the hopes expressed by Bhattacharya, distrust is growing, not decreasing. According to a new KFF survey, only 47% of Americans now say that they trust the CDC “at least ‘a fair amount’ to provide reliable vaccine information”—down 12 percentage points since the beginning of the second Trump administration.
Our nation’s health leaders must do what they can to strengthen, not undermine, trust to better protect the health and lives of Americans and, in the case of Gavi, people around the world. But it’s impossible if they are conditioning funding or making vaccine policy decisions contrary to what the facts say.
Our nation’s health leaders must do what they can to strengthen, not undermine, trust to better protect the health and lives of Americans.
They must be honest about the evidence, especially when it contradicts their belief system, whether the topic is thimerosal, measles, or the data behind the vaccine policies and programs that have saved millions of lives worldwide.
Vaccine Integrity Project Viewpoints are authored by project staff and advisers. They are intended to address timely issues regarding vaccines with straight talk and clarity by presenting facts to counter falsehoods.
