COVID-19 vaccines: 76% of reported side effects may be due to ?nocebo? effect

“It is well-known that expectation contributes significantly to both placebo and nocebo responses in clinical trials.”Dr. Smith said that at Cognivia, “we have come to understand that expectation is itself multidimensional, as there are different types of expectation — including hope and need — that must be considered.”For second doses of vaccines, reported AEs went up from 46% to 61%, while AEs for placebo recipients decreased from 35% to 32%.The authors speculate that the increase for vaccine recipients may relate to their experiences with AEs after the first shot.Dr. Haas suggested that negative expectations may come from “other people who said they had side effects, former experience with side effects of other vaccines or drugs, anxiety or unspecific worries, and the behavior of the clinician, e.g., [do they] show warmth, empathy, competence?”“Furthermore,” noted Dr. Haas, “misattribution of symptoms may play a role.”“This,” said Dr. Haas, “means that you probably have headaches routinely, but if you have a headache the day after the vaccine or placebo shot, you think it was caused by the injection, although it may have occurred anyway.”The authors of the study advocate using open-label placebos, which means that participants are aware they are taking a placebo.