We found that lymphopenia, thrombocytopenia and high levels of ferritin, D-dimer, aspartate aminotransferase, lactate dehydrogenase, C-Reactive Protein, neutrophils, procalcitonin and creatinine are good indicators of both severe and fatal cases of COVID-19 during the first days from illness onset, as is interleukin-6, the main cytokine involved in the CSS. Here, CRP is linked to lymphopenia.