As a W.H.O. member, the United States long sent scientists from the Centers for Disease Control and Prevention to participate in international decision-making about which strains to include in the flu vaccine. A W.H.O. meeting on next year’s vaccine is scheduled for February. The official said the Trump administration would soon disclose how or whether it will participate.
On Thursday, the administration said that all U.S. government funding to the organization had been terminated, and that all assigned federal employees and contractors had been recalled from its Geneva headquarters and its offices worldwide.