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. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial The study is a preliminary retrospective analysis in a setting of health emergency. The project of a clinical trial is under submission to the Ethics Committee. ### Funding Statement The work presented did not receive external fund. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The IRB (Hospital Medical Direction) approval for the use of clinical and laboratory data for the present study has been obtained. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The clinical data used to support the findings of this study are restricted in order to protect patient privacy. Clinical data are available from the corresponding author upon request for researchers who meet the criteria for access to confidential data. The laboratory data used to support the findings of this study are available from the corresponding author upon request.