The reported counterfactual death counts are not reproduced by the dynamic calculation described in the paper, but by a static rescaling: An examination of the mask-wearing counterfactual calculation in Nagata, Okada, and Nishiura (2024)

Using the paper's description and supplementary data, this article examines the mask-wearing counterfactual calculation reported by Nagata, Okada, and Nishiura (2024) and establishes the following two points.First, when the counterfactual effective reproduction numbers are, as the paper describes, brought back into the mathematical model and propagated dynamically, both the cumulative case count and the death count in Tokyo for the lowest-coverage scenario (CF4) become several hundred times the observed values or more. The death count differs from the paper's reported value (about 1.39 times the observed) by orders of magnitude. The cumulative case count is about 1.78 billion, which reaches about 128 times the population of Tokyo in the 28-week computation window. This amounts to every resident of Tokyo being infected about 4.6 times a week; even interpreted as a cumulative count of infection events, it is a scale impossible for any real epidemic.Second, for all four counterfactual scenarios, the reported death counts are reproduced to within 0.22% by a static rescaling that scales the observed case counts and uses neither the maximum-likelihood-estimated weekly effective reproduction numbers R_k nor the age-specific susceptibilities α, β, γ.That is, the reported main results are reproduced without the paper's methodological core—its mathematical model and the estimated parameters {R_k, α, β, γ}.