Abstract
Objectives This study is aimed at exploring the relationship of the viral load of coronavirus disease 2019 (COVID-19) with lymphocyte count, neutrophil count, and C-reactive protein (CRP) and investigating the dynamic change of patients' viral load during the conversion from mild COVID-19 to severe COVID-19, so as to clarify the correlation between the viral load and progression of COVID-19. Methods This paper included 38 COVID-19 patients admitted to the First Hospital of Jiaxing from January 28, 2020, to March 6, 2020, and they were clinically classified according to the Guidelines on the Novel Coronavirus-Infected Pneumonia Diagnosis and Treatment. According to the instructions of the Nucleic Acid Detection Kit for the 2019 novel coronavirus (SARS-CoV-2), respiratory tract specimens (throat swabs) were collected from patients for nucleic acid testing. Patients' lymphocyte count and neutrophil count were determined by blood routine examination, and CRP was measured by biochemical test. Results The results of our study suggested that the cycle threshold (Ct) value of Nucleocapsid protein (N) gene examined by nucleic acid test was markedly positively correlated with lymphocyte count (p = 0.0445, R2 = 0.1203), but negatively correlated with neutrophil count (p = 0.0446, R2 = 0.1167) and CRP (p = 0.0393, R2 = 0.1261), which indicated that patients with a higher viral load tended to have lower lymphocyte count but higher neutrophil count and CRP. Additionally, we detected the dynamic change of Ct value in patients who developed into a severe case, finding that viral load of 3 patients increased before disease progression, whereas this phenomenon was not found in 2 patients with underlying diseases. Conclusion The results of this study demonstrated that viral load of SARS-CoV-2 is significantly negatively correlated with lymphocyte count, but markedly positively correlated with neutrophil count and CRP. The rise of viral load is very likely to be the key factor leading to the overloading of the body's immune response and resulting in the disease progression into severe disease.
Highlights
Since the outbreak of novel coronavirus pneumonia in Wuhan, Hubei Province, China, in December 2019 [1,2,3], the epidemic swept the whole country and other nations in the world and has been lasting till [4,5,6]
Body injury induced by increased viral load triggers the sharp rise in C-reactive protein (CRP) level, and CRP elevation could promote the motion of neutrophil and macrophages, inhibit mixed lymphocyte reaction, and induce inflammatory response in body to resist virus invasion
Increased CRP and decreased lymphocyte both indicated worsening of inflammation, demonstrating that increased viral load would be accompanied by excessive inflammation, which is highly likely to be the key factor contributing to the induction of cytokine storm and development of disease
Summary
Since the outbreak of novel coronavirus pneumonia in Wuhan, Hubei Province, China, in December 2019 [1,2,3], the epidemic swept the whole country and other nations in the world and has been lasting till [4,5,6]. The diagnosis of asymptomatic COVID-19 patients is a tough issue. For suspected cases, they are generally confirmed upon positive nucleic acid testing for the 2019 novel coronavirus (SARS-CoV-2) in sputum, throat swab, and lower respiration secretion by means of Computational and Mathematical Methods in Medicine real-time fluorescence PCR (RT-PCR). RT-PCR can efficiently and quickly finish detecting virus samples, with high sensitivity and specificity. It has become the first detection method recommended in the Guidelines on the Novel Coronavirus-Infected Pneumonia Diagnosis and Treatment (6th edition) [10]
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