CRP and COVID-19: The objective of this study was to evaluate and compare the serum levels of five biomarkers (IL-6, hepcidin, ferritin, C-reactive protein, and zinc) in patients with COVID-19 in intensive care units (ICUs), patients hospitalized with COVID-19 who did not require an ICU and healthy subjects in two Peruvian cities of different altitudes, Lima and Huaraz, to understand the relationship between altitude and COVID-19 biomarkers.