Moderna Inc. shares are selling off Wednesday, after the Trump administration took aim at the science behind the biotechnology company’s vaccines and said it would cancel some contracts and stop funding mRNA drug development.

The US Department of Health and Human Services (HHS) plans to cancel $500m (£376m) in funding for mRNA vaccines being developed to counter viruses like the flu and Covid-19. The move will impact 22 projects being led by major pharmaceutical companies, including Pfizer and Moderna, for vaccines against bird flu and other viruses, HHS said.

That kind of shot was first used during the Covid-19 pandemic, but the health secretary has been sharply critical of the technology.