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.

When COVID-19 cases were surging, Dr. David Wohl saw patients "hungry for air" fill UNC hospital wards. What most saved lives, he said, were vaccines developed with unprecedented speed using mRNA technologies.

This was one in a continuing line of moves that have put Kennedy's vaccine skepticism into public policy, though scientists say the vaccines are safe.