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Comment on “Impact of immune evasion, waning and boosting on dynamics of population mixing between a vaccinated majority and unvaccinated minority” by Fisman et al. (2024): Incorrect definition and application of a parameter ψ
CORRELATION has published a new brief report entitled “Comment on ‘Impact of immune evasion, waning and boosting on dynamics of population mixing between a vaccinated majority and unvaccinated minority’ by Fisman et al. (2024): Incorrect definition and application of a parameter ψ” authored by Denis G. Rancourt and Joseph Hickey.
The report proves that modeling claims, based on an ad hoc mathematical construction (ψ), that unvaccinated people contribute disproportionately (ψ-fold) to the infection risk of vaccinated people are rigorously incorrect. The false claims have a demonstrated potential to cause harm by encouraging overly aggressive public health policies and interventions.
The incorrect construct ψ was first introduced and applied by Fisman et al. in an April 2022 article in the Canadian Medical Association Journal and repeated by Fisman et al. in an April 2024 article in PLOS ONE.
Rancourt and Hickey have written to the editors of PLOS ONE alerting them of the errors in the paper that could cause harm if left uncorrected. From Rancourt and Hickey’s email to the PLOS ONE editors:
“We have prepared a comment consisting of 20 pages, 3 figures, 1 table and 9 references, in which we identify and explain a definite and significant error in the Fisman et al. (2024) article regarding the definition and application of the parameter that the authors refer to as ψ.
We show with examples that the parameter ψ introduced by Fisman et al. has a real potential to cause harm to individuals by encouraging overly aggressive and unnecessary public health policies and interventions.
Our expressed position is that the error of Fisman et al. should be corrected with clear publishers’ notices attached to their articles that apply the parameter ψ.”
Rancourt and Hickey’s previous attempts to correct the Fisman et al.‘s ψ construct include:
- 2023-11-30: J. Hickey & D.G. Rancourt, “Fisman et al.’s Psi (Ψ) index is ill-defined and leads to absurd interpretations”, Correlation Brief Report
- 2023-10-31: J. Hickey & D.G. Rancourt, “Viral respiratory epidemic modelling of societal segregation based on vaccination status”, medRxiv preprint [See Appendix 3 of Version 1 of the preprint, in particular]
- 2022-04-30: Interview about Fisman et al. paper with Dr. Byram Bridle and Dr. Denis Rancourt, Trish Wood is Critical Podcast
- 2022-04-29: D.G. Rancourt & J. Hickey, “Fisman et al.’s main conclusion does not follow from their model”, e-Letter, CMAJ
- 2022-04-27: D.G. Rancourt & J. Hickey, “OCLA Statement on CMAJ Fisman et al. Article Claiming Disproportionate Infection Risk from Unvaccinated Population, and on Negligent Media Reporting”
Download a copy of the report below: