Canadian COVID-19 vaccine study seized on by anti-vaxxers — highlighting dangers of early research in pandemic

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A Canadian study that vastly underestimated the protection COVID-19 vaccines provide against the Omicron variant is being revised — but not before it spread widely on social media by anti-vaxxers, academics and even the creators of the Russian Sputnik V vaccine.

The Ontario preprint study, which has not yet been peer reviewed, suggested that any three doses of mRNA COVID-19 vaccines were just 37 per cent effective against Omicron infection, while two doses actually showed negative protection.

The preprint has been shared on Twitter more than 15,000 times in the two weeks since it's been published, according to Altmetric, a company that tracks where published research is posted online. That's in the top five per cent of all research it's ever tracked.

The group behind Sputnik V shared the results to its one million Twitter followers earlier this month, saying the study showed "negative efficacy" of two mRNA vaccine doses and "quickly waning efficiency" of a booster. The group did not respond to questions from CBC News.

Dr. Vinay Prasad, an associate professor of epidemiology at the University of California-San Francisco, also shared it on Twitter, asking why the U.S Food and Drug Administration (FDA) and Centers for Disease Control (CDC) would advise a booster for Omicron at all.

But the paradoxical findings were later found to have been influenced by behavioural and methodological issues, such as the timing of the observational study, the way in which vaccine passports altered individual risk and changes in access to COVID-19 testing.

The results are currently being updated with additional data that showed completely different results, said Dr. Jeff Kwong, the study's lead author and an epidemiologist and senior scientist at the Institute for Clinical Evaluative Sciences (ICES) in Toronto.

"We're in the process of adding two more weeks of data and it looks like there's no more negative VE (vaccine effectiveness). Our results are now more in line with the data from the U.K. where it's lower, for sure, compared to Delta, but never getting to negative," he told CBC News.

"And then higher VE with the boost. So I think that's good news and we're just in the process of running those analyses and we hope to have an updated version, a version two, by sometime next week." 

A recent report from the Imperial College London COVID-19 response team found that while Omicron largely evades immunity from prior infection and two doses provided just zero to 20 per cent protection, three doses increased that to between 55 and 80 per cent. 

That means the updated preprint could end up showing that protection against Omicron infection is more than twice as high as initially reported. As of Friday, the preprint study remained unchanged on the medRxiv website where it was posted. 

CBC cited the study in an analysis story last week, but has since removed reference to it until the data is updated. 

The study was also highlighted by the federal government's COVID-19 Immunity Task Force earlier this week, before the discrepancies in the data were discovered.