Alamdari et al. [21] investigated MetHb levels in 25 healthy individuals and 25 COVID-19 patients from Iran. Subjects with G6PD deficiency were excluded from the study. Patients showed a statistically significantly higher MetHb concentration in their blood compared to healthy controls (16.4 ± 9.1% vs. 2.5 ± 0.9%). According to the five cases reported in detail in this publication, the medical standard treatment included azithromycin and hydroxychloroquine. To treat the elevated MetHb, methylene blue, ascorbic acid and N-acetyl cysteine were administered. The authors concluded that it is crucial to treat the elevated MetHb in critically ill COVID-19 patients. Soltan et al. [19] used an artificial intelligence method and data from 115,394 emergency presentations and 72,310 admissions to a large UK teaching hospital group to predict COVID-19 cases. The data used were routinely collected data typically available within one hour during emergency presentations and admissions to hospital. Data from COVID-19 patients (n = 534) and pre-pandemic controls (n = 114,957) were included in the final analysis. Interestingly, while MetHb was a relevant parameter to be included in the models (see Figure 3a,b), MetHb was similar in the COVID-19 cohort compared to pre-pandemic controls (0.62% (0.4–0.8%) vs. 0.88% (0.6–1.1%)).