Washington: The US federal government has decided to cancel a major vaccine development contract aimed at protecting against pandemic-prone flu viruses, including the bird flu currently spreading among dairy cattle, according to US media.

According to Anadolu Agency, the decision stems from concerns over the safety of mRNA technology, the US-based National Public Radio (NPR) reported. The Department of Health and Human Services (HHS) announced that it is ending a $766-million agreement with pharmaceutical company Moderna.

The contract was focused on creating an mRNA-based vaccine targeting dangerous flu strains, such as the H5N1 bird flu virus, which has sparked growing alarm in recent months, the department said. "After a rigorous review, we concluded that continued investment in Moderna's H5N1 mRNA vaccine was not scientifically or ethically justifiable," HHS Communications Director Andrew Nixon said in a statement.

"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," Nixon said.