Clinical Significance of Neutralizing Antibodies in COVID-19: Implications for Disease Prognosis

The pathogenesis of COVID-19 highlights a complex relationship between disease severity and neutralizing antibodies (NAbs). We aimed to investigate the relationships among the total NAb (tNAb) levels, the presence of potential neutralization antibodies (pNAbs), and the clinical outcomes of COVID-19 patients. Patients aged ≥18 years diagnosed between October 2021 and September 2022 were grouped by symptom severity. Blood samples were taken at two time points and data on demographics, epidemiology, and vaccination were recorded. The tNAbs and pNAbs were measured by an enhanced chemiluminescence assay and a surrogate virus neutralization test, respectively. The tNAbs of 68 and the pNAbs of 52 patients were analyzed. Twenty-six (38.2%) patients had severe infection. The 28-day mortality rate was 16.2% (n = 11). The tNAb levels in the control blood samples (CBSs) were significantly higher than those of the admission blood samples (ABSs) (<i>p</i> < 0.001). The statistical analysis showed no relationship between disease severity and pNAbs. Vaccinated patients had significantly higher tNAbs in the ABSs and CBSs (<i>p</i> < 0.001 and <i>p</i> < 0.001, respectively). The presence of pNAbs in the ABSs was correlated with a lower 28-day mortality (<i>p</i> = 0.026) and a milder disease course (<i>p</i> = 0.041). Although these findings support a correlation between tNAbs and disease severity and mortality, their presence seems to be unrelated to favorable clinical outcomes.