Short answers, pulled from the story.
The World Health Organization officially began its work on the 1st of September 1948. This start followed a constitution signed by all 51 founding countries of the United Nations and ten other nations.
G. Brock Chisholm was appointed as the director-general after serving as executive secretary during the planning stages. Andrija Štampar became the assembly's first president.
A Global Commission declared in 1979 that smallpox had been eradicated, making it the first disease in history eliminated by human effort. The campaign intensified in 1967 with an annual contribution of $2.4 million from the organization.
On the 30th of January 2020, the World Health Organization declared a Public Health Emergency of International Concern regarding the novel coronavirus outbreak. The agency created an Incident Management Support Team on the 1st of January 2020 to manage the response.
The withdrawal took effect on the 22nd of January 2026, marking the first time in the organization's history that a member state had officially left. U.S. President Donald Trump signed Executive Order 14155 initiating this process on the 20th of January 2025.