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 relationship between total NAb (tNAb) levels, presence of potential neutralization inhibiting 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 enhanced chemiluminescence assay and surrogate virus neutralization test, respectively. Among 68 tNAbs and 52 pNAbs results, 26 (38.2%) patients had a severe infection. The 28-day mortality rate was 16.2% (n=11). The tNAbs levels in the control blood samples (CBS) were significantly higher than those of the admission blood samples (ABS) (p<0.001). The statistical analysis showed no relation between disease severity and tNAb titers. Vaccinated patients had significantly higher tNAbs in ABS and CBS (p<0.001 and p<0.001, respectively). Presence of pNAbs in the ABS correlated with lower 28-day mortality (p=0.026) and milder disease course (p=0.041). Although these findings support a correlation between tNAbs and disease severity and mortality, these seem to be related to their formation rather than their effect on the clinical outcomes.