Researchers find placebo effect accounts for more than two-thirds of COVID-19 vaccine adverse events
The placebo effect is the well-known phenomenon of a person's physical or mental health improving after taking a treatment with no pharmacological therapeutic benefit - a sugar pill, or a syringe full of saline, for example. Sometimes placebo effects can also harm -the so-called "nocebo effect" occurs when a person experiences unpleasant side effects after taking a treatment with no pharmacological effects. That same sugar pill causing nausea, or that syringe full of saline resulting in fatigue.