CAMBRIDGE, MASS. — The US Department of Health and Human Services (HHS) notified pharmaceutical company Moderna Inc. on May 28 that the agency is terminating their $766 million contract for the development of a bird flu vaccine for humans.

“After a rigorous review, we concluded that continued investment in Moderna’s H5N1 mRNA vaccine was not scientifically or ethically justifiable,” said HHS Communications Director Andrew Nixon. “This is not simply about efficacy — it’s about safety, integrity and trust. The reality is that mRNA technology remains under-tested, and we are not going to spend taxpayer dollars repeating the mistakes of the last administration, which concealed legitimate safety concerns from the public.”

The loss of investment ironically came in tandem with Moderna’s announcement of “positive interim data” from a Phase 1/2 clinical study evaluating the safety of the vaccine.

The funding was first awarded to Moderna during the Biden administration in July 2024, with a commitment of $176 million to support the late-stage development of an mRNA-based vaccine. The agreement also included a right to purchase pre-pandemic influenza vaccines.

In January 2025, just before the inauguration of President Donald Trump, HHS sought to accelerate the vaccine development with an additional $590 million award.

After completing an internal review of the project, HHS decided that the research "does not meet the scientific standards or safety expectations required for continued federal investment."

HSS said three other avian flu contracts remain under the National Prepandemic Influenza Vaccine Stockpile (NPIVS) program, but the administration is shifting funding priorities with "better-established safety profiles and transparent data practices."

“While the termination of funding from HHS adds uncertainty, we are pleased by the robust immune response and safety profile observed in this interim analysis of the Phase 1/2 study of our H5 avian flu vaccine, and we will explore alternative paths forward for the program,” said Stéphane Bancel, chief executive officer of Moderna. “These clinical data in pandemic influenza underscore the critical role mRNA technology has played as a countermeasure to emerging health threats.”

The H5-avian-influenza-targeted vaccine, known as mRNA-1018, was evaluated in approximately 300 healthy individuals 18 years or older. The clinical study monitored a two-dose regimen of the investigational vaccine.

mRNA-1018 demonstrated a “rapid, potent and durable immune response,” Moderna said.

According to the Centers for Disease Control and Prevention (CDC), the risk of highly pathogenic avian influenza (HPAI) to the general public remains low.

The agency still has not found evidence of person-to-person spread of the virus. However, the bird flu has led to a total of 70 infections in humans and one reported death.

HPAI has also affected over 173 million birds and more than 1,000 dairy herds as of late May.