Analysis of lymphocyte subsets in COVID-19 patients: a retrospective observational study

In this retrospective study, we analyzed the possible predictive changes in lymphocyte subsets of Coronavirus Disease 19 (COVID-19) hospitalized patients. We enrolled 107 COVID-19 patients older than 18 years of age, admitted to Alessandria Hospital with a confirmed diagnosis of SARS-CoV-2 infection by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR), who performed the analysis of lymphocyte subsets, between 2020 March 01 and 2021 May 31. Patients have been split up into two groups, based on clinical manifestations: group 1 non-severe disease (n=44) and group 2 severe disease (n=63), according to the World Health Organization (WHO) interim guidance. For the comparison between the two groups of patients, statistical significance was tested with the Mann-Whitney and the Chi-Square test. In the group of patients with severe disease, the blood cell analysis showed a significant reduction in the counts of total lymphocytes, absolute CD3 lymphocytes, and CD8 lymphocytes, as well as a significant reduction in monocyte percent and a very significant increase in neutrophil counts. From the results obtained, it can be stated that lymphocytopenia is associated with the progression of the disease and increased mortality.