During the period 1920 to 1950 many experiments were carried out by researchers to establish contagion.. to prove that a healthy individual could become sick from exposure to one with disease.
All were unsuccessful.
Extract..
"During the 'Spanish ' flu epidemic in vivo experiments have conclusively proven that infections cannot be transmitted.
They would not be allowed to be conducted today as it will be seen as unethical. ( on the other hand it is ethical to inject the whole world with an emergency only approved experimental biological injection for an in silico 'virus' that has not been isolated in the true sense of isolation , and thus, the virus and its many variants have not been proven to exist. -"
1993 ".. Dr. Willner replied: “I do this to put a stop to the greatest murderous fraud in medical history. By injecting myself with HIV positive blood, I am proving the point as Dr. Walter Reed did to prove the truth about yellow fever. In this way it is my hope to expose the truth about HIV in the interest of all mankind.” He tested negative multiple times."
Here is the link for detailed information: Contagion – the fairy tale that endures in spite of the contradictory evidence