LAUSR

To the Editors: C OVID-19 pandemic has caused devastating damages to global economy and frightening human deaths worldwide. High transmissibility and fatality of COVID-19 have been an unprecedented challenge to global health. Although more than 80% of COVID-19 cases were mild, 20% of severe and critically ill cases have overburdened the healthcare system of countries with high epidemic. Early identification of the high-risk severe cases is crucial to lower the fatality and healthcare costs. In this study, we retrospectively analyzed the firstand second-week serum levels of interleukin 6 (IL-6), IL-8, and IL-10 of 50 COVID-19 cases (male, 56%; mean age, 51.2 years; range, 18–86 years), including 39 mild cases (78%), 7 severe/ recovered cases (14%), and 4 death cases (8%). All patients were hospitalized within the first week of symptom onsets. The blood testing of each case was conducted at 3rd, 6th, 9th, and 12th days of hospitalization. The ratios of IL-6/IL-10 and IL-8/ IL-10 among mild cases were less than 27 (the highest, 26.9) along the 4 testing points during the 2-week hospitalization, whereas the severe/recovered cases had an up-thendown variation of IL-6/IL-10 and IL-8/IL10 rations with the highest ratio of 45.3 at the ninth day. Importantly, we found that the IL-6/IL-10 and IL-8/IL-10 ratios were as high as 187.51 and 225.3, respectively, in the death group on third day, with the highest IL-6/IL-10 ratio of 297.28 on the sixth day of hospitalization (Fig. 1).