We initiated our work by conducting a bibliographic search in the Medline database (1946 to 1 July 2021) using the following keywords: VZV, chickenpox, varicella, varicella zoster virus, arthritis, “idiopathic purpura fulminans,” “acquired protein S deficiency,” and “anti-protein S antibodies.” The search was limited to publications in English, and the references in the articles were reviewed for all cases of varicella arthritis and purpura fulminans. This evidence concerns the gene PROS1 and purpura.