Changes of peripheral lymphocyte subset in patients with SARS-CoV-2 infection during the whole course of disease.

Background : Little is known about changes in lymphocyte subsets after SARS-CoV-2 infection. Methods : Clinical data of 580 COVID-19 patients hospitalized in Zhongnan Hospital of Wuhan University from 20 December 2019, to 8 March 2020, were retrospectively analyzed. The relation of lymphocyte subsets and severity or prognosis of disease were analyzed. Results : At 2-3 weeks after the onset of symptoms, lymphocyte subsets decreased to the lowest levels. The levels of lymphocyte subsets in asymptomatic patients were close to healthy persons, except for CD8 + T lymphocyte cells. The levels of lymphocyte subsets in patients with severe illness were lower than that in patients with mild-to-moderate illness ( P < 0.01). Similarly, among patients with severe illness, lower levels of lymphocyte subsets were found in dead patients compared to survivors ( P < 0.001). Moreover, by comparing the results of the same patients at different stages of the disease, we found levels of lymphocyte subsets were lower in the acute phase compared to that in convalescent-phase ( P < 0.001). However, the levels of lymphocyte subsets in patients who had SARS-CoV-2 viral load >5000 copies/ml and 500-5000 copies/ml were at similar levels. Conclusions : Lymphocyte subsets are a good biomarker to assess the severity and prognosis of the disease at 2-3 weeks after the onset of symptoms.