From the linked article:
US Officially Exits World Health Organization
The Trump administration cuts funding, recalls U.S. officials from the WHO.
“Today, the United States withdrew from the World Health Organization, freeing itself from its constraints, as President Trump promised on his first day in office,” Secretary of State Marco Rubio and Health and Human Services Secretary Robert Kennedy, Jr., declared in a Jan. 22 joint statement.
“This action responds to the WHO’s failures during the COVID-19 pandemic and seeks to rectify the harm from those failures inflicted on the American people.”
Under the terms of the original agreement establishing U.S. membership, the United States must give the WHO one year’s notice in order to withdraw from the organization. Trump gave such notice to the WHO upon taking office in 2025.