The US Department of Health and Human Services is terminating a contract with drugmaker Moderna to develop a vaccine to protect against bird flu amid the agency’s broader efforts to reevaluate therapies that use mRNA technology.

The Trump administration has canceled $766 million awarded to Moderna to develop a vaccine against potential pandemic influenza viruses, including the H5N1 bird flu.

Health Secretary Robert F. Kennedy Jr. has repeatedly questioned the safety of mRNA technology, which is used in the company’s shot.

The Trump administration has canceled a contract awarded to Moderna for the late-stage development of its bird flu vaccine for humans, as well as the right to purchase shots, the drugmaker announced on Wednesday.

The FDA approved Novavax’s COVID vaccine Nuvaxovid this month, limiting its use to older adults and people over the age of 12 with conditions that put them at risk due to the illness.

Pharmaceutical rivals don’t often come to each other’s defense. But after the US Department of Health and Human Services terminated a contract with drugmaker Moderna to develop an mRNA bird flu vaccine,