IL6 and COVID-19: Inclusion criteria are: 1) age ≥18 years old; 2) diagnosis of SARS-CoV-2 pneumonia confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) of nasopharyngeal swabs or sputum in accordance with the recommendations of the Spanish Ministry of Health; 3) history of symptoms compatible with COVID-19 ≥7 days; 4) hospital admission; 5) at least one of the following: C-reactive protein (CRP) >60 mg/dL, interleukin-6 (IL-6) >40 pg/mL, and/or ferritin >1000 μg/L; and 6) provision of informed consent.