ABSTRACT
The efficacy of coronavirus disease 2019 (COVID-19) vaccination is closely related to the serum levels of SARS-CoV-2-neutralizing antibodies (NAb) that bind to the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. Therefore, the rapid and quantitative measurement of SARS-CoV-2 NAb in the sera of vaccinated individuals is essential to develop an effective vaccine and further achieve population immunity, that is, herd immunity. The plaque reduction neutralization test, the gold standard for NAb effectiveness in serological tests, is accurate but requires biosafety level 3 facilities because of the use of the virus, which hampers its application in common laboratories and clinical practice. Here, we developed a bioresponsive nanogel-based surface plasmon resonance (nSPR) platform that detects SARS-CoV-2 NAb in clinical samples without complicated pretreatment. We found that multivalent protein binding (MPB) between the nanogel-conjugated RBD protein and SARS-CoV-2 NAb yields significantly enhanced SPR signals compared to the nonspecific interference from serum proteins in the nSPR assay. The excellence of our nanogel-based SARS-CoV-2 NAb test is due to its selectivity for NAb, with resistance to all other proteins, allowing the rapid detection and quantification of NAbs in each individual. Importantly, this nSPR assay provides a NAb detection platform for easier and safer COVID-19 vaccination strategies.
ABSTRACT
The COVID-19 pandemic is recognized as one of the most serious global health problems, and many countries implemented lockdown measures to mitigate the effects of the crisis caused by this respiratory infectious disease. In this study, we investigated the relationship between social distancing policies and changes in traffic volume in Sinchon Station, South Korea. We used an official COVID-19 report provided by the Korea Disease Control and Prevention Agency (KCDA) and Seoul Metropolitan Government (SMG) to review social distancing policies, and the changes in traffic patterns before and during the COVID-19 pandemic between January 2020 and November 2021 were analyzed. Our study reveals that the changes in the overall traffic patterns from acceleration phases to deceleration phases of COVID-19 were related to the alert levels of social distancing policies implemented to tackle the situation resulting from the COVID-19 pandemic. Herein, we found that a significant decline in traffic volume took place from August to September 2020 (13.5-19.7%, weekday; 19.4-31.7%, weekend), from December 2020 to January 2021 (20.0%-26.6%, weekday; 26.8-34.0%, weekend), and from July to September 2021 (3.2-13.1%, weekday; 38.3-44.7%, weekend) when compared to the corresponding periods in 2019 (paired t-test; p < 0.001). The results of this study provide strong support for the effectiveness of Seoul's preemptive measures, namely, the central government's intensive social distancing campaign, in managing and reducing the impact of the pandemic situation based on the precise analysis of 10 types of facilities.