Immune assessment of COVID-19 acute disease: associations with disease severity and implications for post-acute outcomes

Abstract Introduction Acute COVID-19 leads to significant morbidity and mortality, often due to respiratory failure and systemic complications. While immune dysfunction is known to underlie severe outcomes, the relationship between hematologic changes and mortality in patients with SARS-CoV-2 remains poorly characterized. This review aimed to analyze alterations in quantitative hematological values in order to establish definitive thresholds or ranges that could be clinically useful in predicting disease severity and preventing COVID-related deaths and long-term consequences. Content We conducted a systematic review following PRISMA regulations of Ovid MEDLINE and Scopus to identify articles that reported differences in hematological values between survivors and nonsurvivors of COVID-19. Results from 42 manuscripts were synthesized by comparing raw hematological values between survivors and nonsurvivors and compared to published basic/clinical data to extrapolate future approaches to detect risks and long-term damage. Summary The analysis resulted in two main conclusions: first, nonsurvivors of COVID-19 had lower RBC counts and poor differentiation, lympocytes, platelet counts, and fibrinogen, and higher MCV, RDW, leukocytes, neutrophils, CRP, and D-dimer with significant indications of coagulation and vascular damage. Secondly, survivors tended to have normal or near-normal lab results as compared to nonsurvivors, except in the case of labs related to bone marrow cell production. Outlook Routine blood tests may provide a low-cost, scalable means of identifying patients at increased risk for severe disease and mortality in acute COVID-19, based on abnormalities in commonly measured hematologic and inflammatory markers; whether these same markers are associated with long-term consequences requires further investigation.