What is the nocebo effect?

Covid-19 has been a major part of our lives in the past few years. From lockdowns to facemasks to social distancing, the rollout of the covid vaccine in late 2020 had been a light at the end of the tunnel.  On 8 December 2020, the first covid vaccine in the world was administered to 90-year-old grandmother, Margaret Keenan in Coventry. This monumental moment was a turning point; from then on, the vaccine roll out in the UK to the wider public was rapid. 

Now in 2022, statistics suggest that over 70% of the UK population are fully vaccinated. That means 139 million doses of vaccines from Pfizer, Moderna, AstraZeneca, Janssen, and even Novavax have been administered in the UK. On a much larger scale, over 10 billion doses have been administered globally and 61.7% of the world population has received at least one dose of a covid-19 vaccine. This number is only going up. The more people we manage to vaccinate, the closer we can get to eradicating the virus. This has been an amazing achievement made by the countless scientists, volunteers, doctors, and healthcare professionals who have worked so hard to protect the public during such a difficult and tumultuous time.

However, there has recently been a greater discussion surrounding the side effects of the covid jab. The NHS website lists a sore arm, tiredness, headaches, feelings of achiness, and/or nausea as the most common side effects of the vaccine. However, researchers have suggested that these negative side effects are not a consequence of the vaccine itself but are in fact a consequence of the phenomenon known as the ‘nocebo effect’. The nocebo effect can simply be described as a negative reaction characterised by the expression of adverse symptoms driven by an individual’s expectation that an unfavourable outcome will occur when a drug, vaccine or medical intervention is administered. 

The nocebo response is extremely common in medical practice; and it can be exploited in drug trials or treatment research

This phenomenon has been highlighted recently in relation to statin treatment; researchers found that the majority of adverse side effects were a consequence of the anticipation of adverse side effects based on prior information provided by a variety of sources, rather than the statin itself. The nocebo response is extremely common in medical practice; and it can be exploited in drug trials or treatment research. 

Due to the amount of media coverage and public interest placed onto the vaccine, there has been a great deal of discussion surrounding the safety and efficacy of the vaccine. As a result, countless articles, videos, and internet posts have been made propagating misleading or down-right incorrect information about the vaccine, leading to an increase in vaccination anxiety. 

The nocebo effect can be activated within a person very easily; the way a drug is packaged, information from the internet, incorrect or misleading media reporting on a drug or vaccine, or even ill-informed comments from friends and families. This can drive an individual into a state of unease or panic when it comes to a treatment option, leading them to believe that a negative outcome is inevitable. 

In a systematic review recently published in the Lancet, researchers compared the rates of adverse side effects in patients either assigned a placebo or an active vaccination. 45,000 subjects were compared; fatigue was reported in 21-29% of patients in the placebo and 24-27% of placebo patients reported a headache. Furthermore, 10-14% of placebo patients reported muscle aches and pains. The researchers therefore concluded that these side effects experienced by the placebo group were as a result of the nocebo effect. This study shows that an increased negative anticipation of the vaccine can potentially induce negative side effects within the population. So, what can we do about this? How can we alleviate people’s concerns about a new and confusing vaccine during such a difficult time? 

In truth, all we can really do is better educate the public. The researchers in the previously mentioned review stated that better public information about nocebo responses may improve covid vaccine uptake by reducing people’s concerns and unease. Reassurance from the government and healthcare professionals, and the removal of harmful, misleading information from internet platforms is a good way to make the public feel less apprehensive about the vaccine.