🧪 Avidity vs Affinity: The Battle of the Bonds 💥 I was talking to my student about one of the most confusing-but-important immunology topics: the difference between avidity and affinity. Affinity = how strongly one antigen-binding site on an antibody attaches to one epitope. Avidity = the overall strength of all the interactions between an antibody and its antigen. So even if each individual bond isn’t the strongest, when there are multiple binding sites, the combined force = high avidity. Tha