RFK Jr. announced a halt to all U.S. funding for the global Gavi vaccine alliance. One expert calls it a "travesty and a nightmare."

Gavi works to expand access to vaccines for children in some of the world’s poorest countries. Health experts say the move could have deadly consequences.

Gavi is a public-private partnership including WHO, UNICEF, the Gates Foundation, and the World Bank. It has paid for more than 1 billion children to be vaccinated through routine immunisation programmes,