Quantitative microfluidic assay to measure neutralizing and total antibodies for SARS-CoV-2

Since the initial coronavirus disease (COVID-19) outbreak in 2019, humans have been adjusting to the pandemic era at the expense of adversity and death. This is due to the lack of definitive vaccines or effective treatments against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern. It is thus essential to assess the immune status of individuals to develop herd immunity. This study aimed to develop a rapid and quantitative antibody-detection-platform, targeting both neutralizing antibodies (NAbs) and total antibodies (TAbs) against SARS-CoV-2, by incorporating nano-interstice channels on a microfluidic chip with digitized flow control. The developed microfluidic platform demonstrated 100 % sensitivity and specificity for clinical samples (n = 38) from COVID-19-positive patients and healthy volunteers. This platform showed a strong correlation and agreement with the plaque-reduction neutralization test (PRNT), the gold standard for NAb assay. The novel assay demonstrated a powerful diagnostic performance, sufficient to replace PRNT or enzyme-linked immunosorbent assay (ELISA). The findings may contribute to COVID-19 management through continuous monitoring of the immune status of individuals and communities.