By comparing mild and moderate cases, we found differences in age, respiratory rate, D-dimer, LDH, and albumin between the two groups, suggesting that old age and hypoproteinemia may be risk factors for progression to moderate COVID-19, and elevated respiratory rate, D-dimer, LDH, AST, urinary creatinine, PCT, and IL6 may indicate the development of moderate COVID-19. Here, IL6 is linked to COVID-19.