https://www.trumanlibrary.gov/library/executive-orders/10399/executive-order-10399
Harry Truman's Executive Order ceded authority of public health to WHO in 1952 via EXECUTIVE ORDER 10399:
September 27, 1952
EXECUTIVE ORDER 10399
DESIGNATING THE SURGEON GENERAL OF THE PUBLIC HEALTH SERVICE TO PERFORM CERTAIN DUTIES UNDER THE INTERNATIONAL SANITARY REGULATIONS (WORLD HEALTH ORGANIZATION REGULATIONS NO. 2)
WHEREAS, under Articles 21 and 22 of the Constitution of the World Health Organization, adopted in New York on July 22, 1946, accepted June 14, 1948, on behalf of the United States of America by the President acting pursuant to the authority granted by the joint resolution of the Congress of the United States of America approved June 14, 1948 (Public Law 643 80th Congress, 22 U.S.C. 290), the Government of the United States of America, together with the governments of other countries which have accepted the said Constitution, undertakes to give effect to regulations of the World Health Assembly concerning sanitary and quarantine requirements and other procedures designed to prevent the international spread of disease, as to which the said governments have not entered an unacceptable reservation or a rejection; and
WHEREAS the World Health Assembly on May 25, 1951, adopted International Sanitary Regulations (World Health Organization Regulations No. 2) concerning sanitary and quarantine measures which may be imposed on international traffic to prevent the international traffic to prevent the international spread of smallpox, plague, cholera, yellow fever, typhus, and relapsing fever, as well as concerning reports and notifications of outbreaks of such diseases; and
WHEREAS the said International Sanitary Regulations have been accepted by the Government of the United States of America without reservation and come into force on October 1, 1952, with respect to the said Government and the governments of certain other countries; and
WHEREAS, in order that the Government of the United States of America may give full and complete effect to the said regulations and assist in the prevention of the international spread of disease, it is necessary that an agency of the executive branch of the said Government be designated to exercise functions and perform duties under the said regulations; and
WHEREAS authority and responsibility for the prevention of the introduction, transmission, or spread of communicable diseases from foreign countries into the States and possessions of the United States of America already vested in the Surgeon General of the Public Health Service, Federal Security Agency, pursuant to the Public Health Service Act (Public Law 410, 78th Congress; 42 U.S.C. 201, et seq.):
NOW, THEREFORE, by virtue of and pursuant to the authority vested in me as President of the United States of America, I hereby designate the Surgeon General of the Public Health Service in the Federal Security Agency as the "health administration" of the United States of America for the purpose of performing the duties prescribed and undertaken in the said International Sanitary Regulations.
HARRY S. TRUMAN
THE WHITE HOUSE,
September 27, 1952.
https://www.trumanlibrary.gov/library/executive-orders/10399/executive-order-10399