Pawlowski et al. [25] found that, when comparing 246 SARS-CoV-2 PCR-positive patients to propensity-matched 2460 SARS-CoV-2 PCR-negative patients, COHb at clinical presentation was actually slightly, but significantly, higher in the SARS-CoV-2 PCR-negative population (0.99 vs. 0.57%) (Figure 2b).