Longitudinal hematologic and immunologic variations associated with the progression of COVID-19 patients in China

ABSTRACT

Background Crucial roles of hematologic and immunologic responses in progression of COVID-19 remains largely unclear. Objective We sought to address the dynamic changes of hematologic and immunologic biomarkers and their associations with severity and outcomes of the disease. Methods A retrospective study including 548 COVID-19 patients with clarified outcome (discharged or deceased) from a national cohort in China was performed. Cross-sectional and longitudinal variations were compared and the associations with different severity and outcomes were analyzed. Results On admission, the counts of lymphocytes, T cell subsets, eosinophils and platelets decreased markedly, especially in severe/critical and fatal patients. Increased neutrophil count and neutrophils-to-lymphocytes ratio were predominant in severe/critical cases or non-survivors. During hospitalization, eosinophils, lymphocytes and platelets were shown an increasing trend in survivors, but maintained lower levels or dropped significantly afterwards in non-survivors. Non-survivors kept high level or showed an upward trend for neutrophils, IL-6, procalcitonin, D-dimer, amyloid A protein and C-reactive protein, which were kept stable or shown downward trend in survivors. Positive correlation between CD8+ T cell and lymphocytes count was found in survivors but not in non-survivors. A multivariate Cox regression model suggested that restored levels of lymphocytes, eosinophils and platelets could serve as the predictors for the recovery, while progressive increases in neutrophils, basophils and IL-6 were associated with fatal outcome. Conclusions Hematologic and immunologic impairment showed a significantly different profile between survivors and non-survivors in COVID-19 patients with different severity. The longitudinal variations of these biomarkers could serve to predict recovery or fatal outcome.