Dynamic changes of the neutralizing antibodies levels in COVID-19
patients as a potential tool in differential diagnosis
Abstract
Background: Neutralizing antibody (NAb) is an important immunological
marker in Coronavirus disease 2019 (COVID-19). This study aims to
explore the different changes of NAbs level in COVID-19 patients and
screen specific laboratory findings to predict disease severity.
Methods: Eighty-eight COVID-19 patients, forty-eight healthy controls
and sixty-two healthy vaccinated people were included. Epidemiological,
clinical and laboratory data were obtained from the electronic medical
record information system. The NAbs levels were determined by the double
antibody sandwich method. The first set of laboratory results of the
COVID-19 patients was selected after onset to construct the receiver
operating characteristic curve (ROC). Correlation curves were also
constructed to explore the relationship between laboratory findings and
NAbs. Results: In mild cases of COVID-19, NAbs levels reached the peak
at 25-30 days after onset. NAbs levels during convalescence were lower
than those after onset and were found to gradually decrease during 0-15
days. In severe cases, NAbs levels peaked at 20-25 days after onset. The
ROC analysis demonstrated that the area under the curve of C-reactive
protein (CRP) was 0.94 at 20.42 mg/L cut-off with sensitivity and
specificity of 100% and 82% respectively. The levels of NAbs, CRP,
glucose (Glu), neutrophils (NE) and urea nitrogen (Urea) in mild cases
were lower than those in severe cases (p<0.05). Correlation
analysis showed that CRP was positively associated with NAbs.
Conclusion: The levels of NAbs dynamically changes at different stages
in COVID-19 patients with various severities. CRP and other laboratory
findings provide the basis for clinical differential diagnosis.