https://www.sciencedaily.com/releases/2021/01/210113144447.htm > Ohio State University researchers reviewed 49 vaccine studies in humans dating back 30 years that document how stress, depression and poor health behaviors can negatively affect the body's immune response to vaccination, and how improving health factors can enhance that response. > The impaired immune responses tended to fall into three categories -- interference with the development of antibodies against the pathogen, more rapid erosion of antibody protection that does develop, or intensification of vaccination's side effects.