Rapid and Low-Cost Detection and Quantification of SARS-CoV-2 Antibody Titers of ICU Patients with Respiratory Deterioration Using a Handheld Thermo-Photonic Device

While research suggests that COVID‐19 vaccines are effective in producing anti‐SARS‐ CoV‐2 antibodies that reduce the risk of COVID‐19 and its potentially severe complications, how long these antibodies persist after the infection/vaccination is unknown. Longitudinal studies and rapid and scalable platforms are needed for large‐scale sero‐diagnosis and vaccine evaluation. In this study, we examine the efficacy of our recently‐developed handheld thermo‐photonic device for rapid and low‐cost assessment of the adaptive immune response of COVID⁺ and COVID⁻ patients admitted to the intensive care unit (ICU) at a local hospital due to respiratory deterioration. Antibody testing included detection and quantification of IgG and IgM via thermo‐photonic sensing of a commercially available COVID‐19 IgG/IgM rapid test as well as standard measurements with quantitative enzyme‐linked immunosorbent assays (qELISA). The results demonstrate that the thermo‐photonic reader in conjunction with COVID‐19 IgG/IgM test cassettes can detect and quan-tify IgG levels in COVID‐19 antibody assays within the clinically relevant range and with a high correlation to those obtained from qELISA. We also found that the IgG antibody is more reliable for detecting individuals with an adaptive immune response to SARS‐CoV‐2 compared to the IgM an-tibody. The developed reader offers a low‐cost, portable, and scalable solution for accessing the antibody titer of individuals against SARS‐CoV‐2 and can be used in local hospital settings.