TORONTO -- Facebook communities pushing misinformation about COVID-19 vaccines in Canada have grown by 48 per cent in the past six months, according to a new report by a U.K. think tank that specializes in monitoring disinformation, extremism and hate online.

Analysts at the Institute for Strategic Dialogue (ISD) in London say they have identified 33 Facebook pages and 45 public groups in Canada that regularly feature COVID-19 vaccine misinformation. After taking a deep dive into their content, the ISD says there are tens of thousands of posts that promote suspicion and anger about vaccines, which they say can lead to real-life harassment and violence.

As of March 1, there were more than 432,000 Facebook users who liked pages or joined groups that shared misinformation related to the pandemic, compared to 291,200 users in September 2020.

“A recurring theme in online COVID-19 vaccine disinformation revolves around the baseless claim that [Moderna] vaccines will cause a ‘cytokine storm,’ or an auto-immune response in those vaccinated, who will then become ill or die after receiving it,” the report says.

According to the ISD, videos of anti-vaccination activists promoting the baseless ‘cytokine storm’ claim have been shared more than 6,000 times on Facebook. Two versions of the video now feature a fact check warning label, while two others do not. The institute says this highlights “an inconsistent approach from Facebook to fact-checking similar pieces of misleading COVID-19 vaccine content.”

A representative for Facebook did not respond to CTV News’ request for comment by the time of publication.

Analysts at the ISD say they began their work by identifying a comprehensive list of keywords to capture the discourse on vaccines on Facebook. Some of the keywords include: Moderna, Pfizer, BioNTech, AstraZeneca, Janssen and COVID-19 vaccine.

Researchers then used the keywords in combination with online monitoring tools like CrowdTangle to search through Facebook pages and public groups in various countries that posted, shared or hosted content containing COVID-19 vaccine misinformation throughout 2020 and 2021.

Analysts say they were able to use data from CrowdTangle to assess the number of comments, shares and reactions on each post. However, due to limited access, any posts or comments made in private Facebook groups and personal profiles were outside the bounds of analysis, the IDS says.

In addition to general misinformation about vaccines, analysts also found conspiracy theories about the rollout of vaccines in Canada and their impact on society.

“On 11 February, Prime Minister Justin Trudeau said that there could be [public health] ‘consequences’ for people who do not get vaccinated – a comment that triggered a spike in China-related conspiracies among online communities,” the report notes.

Researchers also noted that news reports about the pandemic are being shared on Facebook and used to direct slurs, threats and hatred toward public figures like Canada’s top doctor, Theresa Tam.

“This research illustrates how the process of vaccine rollout can be undermined by online misinformation,” the report notes. “Tackling COVID-19 vaccine misinformation is an essential step in boosting public confidence in vaccines.”

“The responses of social media platforms, governments and health institutions to this misinformation will be a crucial component in allowing societies to emerge as quickly as possible from the pandemic.”