Peripheral blood immune status at clinical onset correlates with severity of Coronavirus Disease 2019

The Coronavirus Disease 2019 (COVID-19) pandemic is a global threat to healthcare systems, requiring hospitalization in sub intensive and intensive care for respiratory syndrome in 25-30% of patients and accounting for a lethality up to 15%. In this retrospective study the clinical characteristics of 215 COVID-19 patients were correlated with the peripheral blood immune status. Different groups of COVID-19 patients may be identified on the basis of clinical behavior and a strong correlation between groups and age and comorbidities as well as with the immune profile is demonstrated. A lower age correlates with a lower severity of the disease differentiating between patients who may be quarantined at home and those requiring hospitalization. An older age (>82 years) together with a higher number of comorbidities is associated to a very severe prognosis. The absolute number of CD3+, CD4+, CD8+ T lymphocytes was progressively decreasing according to the severity of the disease and a CD3+ and CD8+ threshold indicating very severe cases is suggested.