Two-thirds of Covid jab reactions not caused by vaccine, study suggests

‘Nocebo effect’: two-thirds of Covid jab reactions not caused by vaccine, study suggests US researchers show negative version of placebo effect behind many symptoms such as headaches and fatigue the Guardian

More than two-thirds of the common side-effects people experience after a Covid jab can be attributed to a negative version of the placebo effect rather than the vaccine itself, researchers claim.

Scientists in the US examined data from 12 clinical trials of Covid vaccines and found that the “nocebo effect” accounted for about 76% of all common adverse reactions after the first dose and nearly 52% after the second dose.

The findings sgest that a substantial proportion of milder side-effects, such as headaches, short-term fatigue, and arm pain are not produced by the constituents of the vaccine, but by other factors thought to generate the nocebo response, including anxiety, expectation and misattributing various ailments to having had the jab.

“Telling patients that the intervention they are taking has side-effects that are similar to placebo treatments for the condition in randomised controlled trials actually reduces anxiety and makes patients take a moment to consider the side-effect,” said Ted Kaptchuk, professor of global health and social medicine at Harvard medical school, and a senior author on the study. “But we need more research.”...