The World Health Organization is shaped by its members: 194 countries that set health priorities and make agreements about how to share critical data, treatments, and vaccines during international emergencies.

Public health experts say the United States’ departure could cripple the WHO’s operations or leave an opening for China to assume greater control over the agency.

President Donald Trump signed an executive order that would begin the process of removing the U.S. from the World Health Organization. Here's why.