Innovative Test Visualizes SARS-CoV-2 Antibody Levels in Real Time

Increasing evidence suggests SARS-CoV-2 coronavirus antibody levels are correlated to immune protection, which is useful when choosing vaccine types and monitoring its decay over time.

But its quantitation relies on intensive laboratory techniques.

On May 3, 2022, Science Advances published a report on a decentralized, instrument-free microfluidic device that directly visualizes SARS-CoV-2 antibody levels.

Magnetic microparticles (MMPs) and polystyrene microparticles (PMPs) can bind to SARS-CoV-2 antibodies simultaneously.

In a microfluidic chip, this binding reduces the incidence of free PMPs escaping from magnetic separation and shortens PMP accumulation length at a particle dam.

This visual, quantitative result enables use in either sensitive mode [limit of detection (LOD): 13.3 ng/ml; sample-to-answer time: 70 min] or rapid mode (LOD: 57.8 ng/ml; sample-to-answer time: 20 min) and closely agrees with the gold standard enzyme-linked immunosorbent assay.

Trials on 91 vaccinees revealed higher antibody levels in mRNA vaccinees than inactivated vaccinees and their decay in 45 days, demonstrating the need for point-of-care devices to monitor immune protection.

'Similar to an ordinary mercury thermometer, the result is readable and unambiguous.'

'Thus, our device is particularly suitable for the general public to routinely check immune protection at local clinics.'

Furthermore, these researchers from the University of Hong Kong suggested that antibody-based 'immunity passports 'instead of vaccination records might offer enhanced evaluations before flight travel.

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