PROS1 and Autoimmunity: A second more convincing hypothesis is related to molecular mimicry, as demonstrated by an in vitro study revealing a strong cross-reactivity between antibodies against protein S (the protein that binds to ACE2 receptors and allows the virus to enter the cell) and a number of antigens, including TPO, which could account for autoimmunity and inflammatory reactions observed in both SARS-CoV-2 infection and vaccination in genetically predisposed individuals [111,114,115].