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- Page navigation anchor for RE: Alternate Realities of COVID-19 in CanadaRE: Alternate Realities of COVID-19 in Canada
Razak et al. caution against deliberately inferring causation between the interventions and outcomes of the pandemic when comparing Canada to 11 "peer" nations [1]. However, despite repeated mention of the issue, the authors appear to pick-and-choose when to exercise that caution.
My attention was drawn to their use of counterfactual (or "alternate reality") scenarios to discuss how much worse Canada's Covid-19 outcomes "could have been" with France-like infection rates or US-like vaccine coverage. Counterfactuals, by definition, are tied to causation and—most importantly—require background conditions to be exchangeable to draw sensible conclusions [2-3]. It does not appear that Razak et al. have reflected upon how fundamentally different Canada's base case would need to be under these scenarios. For example, transmission rates depend on host density: the closer people are to one another, the more likely they will spread infection [4].
I also find it unlikely that a US-like vaccine coverage would have resulted in 68,800 additional deaths in Canada. Vaccine coverage quantifies "how many" people have been vaccinated, not "whom". This scenario relies on assuming that every unvaccinated person is equally at-risk of dying, when instead, severe outcomes are most-frequently observed amongst the elderly and the chronically, critically ill. If, under a US-like scenario, all 5.9 million unvaccinated people wer...
Show MoreCompeting Interests: None declared.References
- 1. Razak F, et al. CMAJ 2022, June 27; 194: E870-7. Link: https://doi.org/10.1503/cmaj.220316
- 2. Pearl J. Causal and Counterfactual Inference, in The Handbook of Rationality, 2021; pp. 427-438, The MIT Press. Link: https://ftp.cs.ucla.edu/pub/stat_ser/r485.pdf
- 3. Bours MJL. J Clin Epidemiol 2020, May 1; 121: 91-100. Link: https://www.jclinepi.com/article/S0895-4356(19)30173-8/fulltext
- 4. Anderson RM, May RM. J. Animal Ecol 1978; February; 47: 219-47. Link: https://doi.org/10.2307/3933