Did you experience a headache or fatigue after your Covid-19 vaccine? It might not have been caused by a vaccine side effect after all.
Some “side effects” that people experience after a Covid jab might be due to a negative version of the placebo effect, rather than the actual vaccine, new research suggests.
Scientists in the US examined data from 12 clinical trials of Covid vaccines, in which half the participants were given the Covid jab and half a placebo salt solution. The researchers found that the “nocebo effect” made up for over two-thirds (76%) of all common reactions after the first jab and almost 52% after the second.
The research highlights that a large amount of milder side effects – such as headaches, short-term fatigue and arm pain – are often the result of a nocebo response rather than the vaccine itself.
The researchers say other causes including anxiety and expectation are likely to have prompted some misattribution of symptoms to having had the jab.
Experiencing side effects after having a vaccine is normal, including the Covid-19 vaccine. Analysis of data from the Zoe Covid Symptom Study app found that one in four people experience “mild, short lived” side effects after receiving either the Pfizer or AstraZeneca vaccine.
A sore arm has been reported as one of the most common side effects of the Covid jab, according to the study, and scientists around the world have agreed that the benefits far outweigh any small risks.
The researchers of the latest study, published in the journal Jama Network Open, hope the results will help Covid vaccine uptake, because it may limit the worries of those who are vaccine hesitant.
Ted Kaptchuk, professor of global health and social medicine at Harvard medical school, and a senior author on the study, told The Guardian: “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.”
That’s not to say that side effects don’t exist at all, or that symptoms prompted by anxiety are any less important.
If you’re experiencing mild side effects like aches, pains and fever, the NHS suggests taking a painkiller such as paracetamol. It’s quite common to get a mild fever after the vaccine which normally resolves itself in roughly 48 hours – if you have a fever for longer, or any other symptoms of the virus, consider getting a Covid-19 test.
If you have other symptoms that become worse or start to cause concern, you should seek medical assistance by calling 111 or your GP practice. In an emergency, phone 999.
