Don't let psychogenic illness undermine the Covid vaccine: An open letter to journalists

Opinion surveys show that many people are hesitant to be vaccinated for Covid-19 over safety concerns. Even before the world had heard of the coronavirus, in 2019 the World Health Organisation was warning that “vaccine hesitancy” was a major threat to global health (WHO 2019). Reticence to be vaccinated has been blamed for increases in preventable disease outbreaks around the world.

Also concerning is the number of mass hysteria outbreaks triggered by vaccination campaigns. This is a serious issue because any outbreak of psychogenic illness could undermine public confidence in the safety of a Covid-19 vaccine.  

How serious is the problem?

Outbreaks of mass psychogenic illness triggered by vaccinations have been documented in at least a dozen countries since 1992, including Iran (1992), Italy (1995), Jordan (1998), India (2001), Vietnam (2001), Australia (2007), Taiwan (2009), the United States (2010), Japan (2013), Colombia (2014), Denmark (2015), and Brazil (2019). There are also many media reports describing events that were never written up as formal studies, where doctors told journalists that the likely cause was psychological.

A similar event could damage public confidence in vaccine safety and reduce the number of people who will be open to receiving the vaccine. In 2014, Colombian researchers identified an outbreak of psychogenic illness among several hundred girls who had been injected with the Gardasil vaccine, which targets the human papillomavirus (HPV). As a result, the uptake rate for the HPV vaccine plummeted to 14% for the first dose and just 5% for the second injection, leaving girls in the affected group at higher risk for cervical cancer. A similar plunge in uptake rates took place in Vietnam during a psychogenic outbreak in 2001, when children were being inoculated for cholera. Of the 97 children affected, only two were allowed by their guardians to receive a second dose.   

Awareness and identification

The media and the public need to be aware of the likelihood of psychogenic clusters. What will they look like? Psychogenic events will involve the clustering of transient, benign symptoms that appear shortly after vaccination. Outbreaks of mass psychogenic illness associated with past vaccinations most commonly include headache, nausea, dizziness, breathlessness, and fainting. These complaints are characterised by a rapid onset and recovery. If this occurs, mass psychogenic illness should be a prime suspect.  

Remember, serious side effects of vaccines are rare. The problem is, media reports have been shown to increase the frequency of psychogenic symptoms. Media stories of vaccine side effects can give the misimpression that such reactions are more frequent than they are, increasing anxiety about the vaccine. Studies have shown that media coverage of side effects of certain medications can increase the number of adverse symptoms, particularly the specific symptoms mentioned in the news item.

It is important to remember that any vaccine that has been approved for widespread use will have adverse reactions ranging from mild to severe. However, mass psychogenic illness should be suspected when there is a clustering of symptoms. Given the large number of people who are expected to be vaccinated, it would be surprising if several clusters of psychogenic reactions do not appear. Historical outbreaks of psychogenic illness have often been met with suspicion and hostility and can spread in the form of misinformation, rumors, and conspiracy theories. Media outlets need to be aware that psychogenic clusters are likely to appear – and if they do, it is important to report on the event in a calm, measured tone until the origin of the outbreak is ascertained.