This study aims to provide an accurate tool that allows patients to be classified "a priori" according to their probability of success in responding to one of the immunosuppressive biological drugs that are currently being administered to combat SARS-CoV-2 infection, Tocilizumab. Tocilizumab is an interleukin-6 (IL-6) cell receptor blocker, which has been shown to be effective in fighting SARS-CoV-2 infection in different pre-clinical studies and is currently indicated for prescription in patients with a moderate level of severity of lung involvement. Likewise, different cynical trials have been initiated, in China (ChiCTR2000029765) and Italy, in patients with pneumonia and early respiratory failure (Favalli et al. 2020, PMID: 32205186).With the recent SARS-CoV-2 pandemic, different lines of research have shown that, more than the virus itself, what really aggravates the situation of infected patients, is the "cytokine storm" (Prompetchara et al. 2020, PMID: 32105090). This phenomenon, which can lead to the onset of viral sepsis, inflammation-induced lung damage, and even death, it results from dysregulation of the patient's immune system when trying to fight the virus. This "cytokine storm" is made up of very high levels of proinflammatory cytokines such as Interleukin-1β (IL-1β), IL-2, IL-6, IL-7, IL-8, tumor necrosis factor-α ( TNF-α) and chemokines such as CXCL10 or CCL2 among others, together with a significant degree of lymphopenia and a drastic decrease in Interferon (IFN) (Favalli et al. 2020, PMID: 32205186). Specifically, the increase in IL-6 associated with severe pneumonia can have deleterious effects on the adaptive immune response (sarzi-Puttini et al. 2020, PMID: 32202240).