The United States has unlocked frozen Gavi funding, resolving a bitter political impasse in Washington while doubling down against the WHO. But can the alliance eliminate thimerosal, a mercury-containing preservative, from its stockpiles without leaving millions of vulnerable children unprotected?

The United States will immediately release $600 million for fiscal years 2025–2026 in frozen Gavi funding, ending a tense congressional stand-off that threatened global immunisation plans, the US announced in a joint media note by the State Department and Department of Health and Human Services (HHS). The decision follows a bipartisan campaign led by Senate Appropriations Committee Chair Susan Collins and Vice Chair Patty Murray, who urged Secretary of State Marco Rubio to restore the funds.

However, the US money comes with a strict caveat, demanding Gavi work towards transitioning away from vaccines that use thimerosal as a preservative. “The Administration believes reducing reliance on mercury-containing vaccines, where suitable alternatives are available, is a pro-vaccine, pro-innovation policy,” the statement declared. Secretary of Health and Human Services Robert F Kennedy Jr reportedly associates the preservative with autism, a claim that international scientific bodies and paediatricians have repeatedly rejected.

In a press release on Thursday, Gavi welcomed the US decision. “This investment will help us to strengthen global defences against outbreaks and pandemics and protect more children from preventable diseases,” Gavi Chief Executive Officer Sania Nishtar said.

The breakthrough strengthens Gavi’s recalibrated $10.2 billion strategic budget, keeping the alliance on track to meet its 2026–2030 mobilisation goals. According to recent Gavi board projections, the partnership has already secured $9.3 billion in qualifying resources, including $2.7 billion formally signed in donor agreements.

Gavi insists science guides portfolio decisions

The State Department said Gavi committed to work towards transitioning away from using thimerosal as a vaccine preservative to unlock the funding.

Responding to a query by Health Policy Watch, Gavi noted that transitions were already underway but had previously stalled due to financial constraints. The alliance “began supporting adoption of the hexavalent and multivalent meningococcal conjugate vaccines (MMCV) in 2023,” highlighting these newer vaccine options. However, Gavi explained that “progress has been held back due to funding challenges”.

The alliance also insisted that its medical portfolio remains anchored strictly in global science. “Gavi always has and always will be guided by the global scientific consensus,” the alliance stated. It added that any portfolio changes remain “subject to Gavi Board approval and dependent on factors including country demand, programmatic context, global manufacturing capacity and affordability”.

No scientific evidence for autism claims

The American Academy of Pediatrics (AAP) and the European Medicines Agency (EMA) have repeatedly reviewed clinical safety evidence, confirming that the preservative is safe. Expert fact-checks of the scientific evidence reiterate that “extensive research proves that thimerosal is a safe ingredient in vaccines, and it does not cause neurological problems or autism”.

While the US and Europe transitioned to single-dose, mercury-free vaccines 25 years ago, developing countries still rely on cheaper multi-dose vials, where thimerosal is used to destroy any bacteria and fungi that may enter a vial each time a new dose is drawn.

Around 14% of Gavi vaccines contain thimerosal, including the five-in-one pentavalent vaccine (Diphtheria, Pertussis, Tetanus, Hepatitis B and Haemophilus influenzae type b), the Diphtheria, Pertussis and Tetanus (DPT) vaccine, Tetanus-Reduced Diphtheria (Td), Hepatitis B, Meningococcal A Conjugate (MenA) and Pneumococcal Conjugate Vaccine (PCV).

Gavi funding fire-walled from WHO

In addition, the US placed another strict financial firewall on its restored $600 million contribution, explicitly demanding that no American taxpayer funds reach the World Health Organization (WHO) through Gavi – even though the two global health bodies collaborate closely.

“The United States also reaffirms that it will not provide US Government funding to the World Health Organization through Gavi,” said the joint State Department and HHS media note.

While Gavi accepted the funding, legally binding the alliance to the US donor restrictions, it bypassed the political blockade with a simple accounting adjustment. Gavi explained that since the WHO is a core partner, its funding “is already accounted for through existing funding” from other international donors.

The US boycott of WHO reflects the deep and continuing diplomatic fracture with President Donald Trump, ever since he signed an executive order to exit the global health agency in January 2025, plunging the WHO into a severe financial crisis. Although Washington declared its withdrawal complete in early 2026, the WHO refuses to recognise the departure because the US has failed to pay outstanding dues.

A query to the WHO asking for comment on the funding firewall remained unanswered.

Despite a lack of scientific evidence supporting the US administration’s safety claims, Gavi will have to navigate these political demands while striving to reach its vaccination goals so as not to leave vulnerable children behind.

See related story:

US Freezes All Funds to Gavi Over Vaccine Preservative Thimerosal

Image Credits: Nana Kofi Acquah, Felix Sassmannshausen/HPW.