The top public health officials during Trump's first term praised mRNA vaccines. In the second term, officials seem to be retreating from them.

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.

This speeding up of the production process is one of the key reasons mRNA vaccines have "long been distrusted by vaccine sceptics". Kennedy himself referred to mRNA vaccine technology as "troubled", and called older "whole-cell" vaccine technology "safer".