Long before the emergence of COVID-19, the World Health Organization identified vaccine reluctance as one of the main threats to human health around the world.
In a new article published in the journal BMC Public Health, a group of Concordia researchers examines both the side effects reported by vaccinees – known as ‘adverse events’ or AEs – and the cognitive biases identified among those who are hesitant about vaccination.
“We started our work on this article at the end of 2019, before we even heard of COVID-19,” says Hossein Azarpanah, lead author of the article and doctoral student in the Department of Supply Chain Management and corporate technologies from John Molson School. work.
“Reluctance to vaccinate has been a problem for as long as we have vaccines. But over the past 10 to 15 years, mainly through social media, people have formed these integrated groups online and have had significant influence even before the pandemic. “
Assistant Professor Mohsen Farhadloo and Professor Rustam Vahidov, both in the same department as Azarpanah, and Louise Pilote, professor of epidemiology at McGill University, co-authored the study.
Data-driven evidence to answer vaccine safety concerns
For the first part of their study, the researchers looked at two public databases, the US-based Vaccine Adverse Event Reporting System (VAERS) and the Canada Vigilance online adverse reaction database. They found that minor vaccine-related adverse events were common, but the vaccines themselves were very safe.
Between January 1, 2011 and December 31, 2018, the VAERS database received nearly 295,000 reports, or about 115 reports per million people, on 87 different vaccine types. The most commonly reported types of vaccines were against chickenpox, two types of influenza, pneumococcal bacteria and human papillomavirus. Median reports were for three adverse events, the most common being rash, fever, swelling, and local aches or pains, extremity or head. Some 5.5 percent reported serious adverse events, resulting in hospitalization, disability, death or death threats. The top five side effects in these cases were fever, pain, vomiting, headache, and shortness of breath. The results from the Canadian database were consistent with those from the VAERS. The authors also created a dashboard that can be used to visualize the results of the study.
The researchers also note that the most effective way to communicate vaccine safety is to write summary reports. Overly detailed reporting can lead to increased cognitive bias, which can negatively influence a person’s decision to receive a vaccine.
Fifteen types of cognitive bias
In the second part of the study, the researchers examine the cognitive biases that underlie vaccine hesitancy. They identified 15 possible biases and assessed how each might cause an individual to decide not to receive a vaccine. These include, among others:
Availability bias: The tendency to assign a higher weight to factors that are easier to remember, such as a vivid memory of a rare case of a person suffering from serious adverse events.
Optimism bias: Minimize or have an unrealistic and optimistic view of health risks.
Shared information bias: The tendency, often seen in social media groups, to spend more time and energy on familiar information and less on new information.
Other forms of bias include authority bias (a celebrity or prominent politician makes claims about the validity of a certain drug or vaccine); aversion to ambiguity (a known risk is better than an unknown risk); current bias (today’s effects matter more than tomorrow’s); confirmation bias (preferring information that confirms existing beliefs) and belief bias (evaluating an argument based on the credibility of the conclusion).
For Farhadloo, this framework, when coupled with data analyzed in the VAERS and Canada Vigilance databases, provides communicators with the tools that can help counter the growing spread of disinformation.
“We analyzed existing reports and found no evidence linking the severity of adverse events to vaccinations,” he says. “For health officials, applying our findings and paying attention to how they communicate can be important tools when dealing with misinformation on social media.”
Read the cited article:
“Reluctance to Vaccination: Evidence of Adverse Events After the Vaccination Database and Role of Cognitive Bias”.
– By Patrick Lejtenyi
– Concordia University
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