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.

Health and Human Services Secretary Robert F. Kennedy Jr. said this week that he's pulling the plug on nearly $500 million in funding for the development of mRNA vaccines. Here's how they work. Vaccines using mRNA technology weren’t immune to the latest round of federal research cuts.

While anti-vaxxers are thrilled, experts warn that defunding mRNA development takes away our already-proven best weapon against future pandemics.