Toward rapid and sensitive point‐of‐care diagnosis with surface‐enhanced Raman scattering‐based optofluidic systems

With the recent global outbreaks of infectious diseases such as coronavirus disease 2019, developing a detection system capable of quickly and accurately diagnosing diseases on‐site has become a pressing need. The ability to diagnose patients in the field is crucial for the prompt isolation and treatment of infected individuals and the prevention of the spread of the disease. Our research group has recently developed a surface‐enhanced Raman scattering optofluidic system that enables rapid and accurate point‐of‐care diagnostics. This account will introduce the principle and configuration of the fluidic devices, such as lateral flow assay strips or microfluidic channels, and the portable Raman spectrometer. We will also highlight the challenges that must be addressed for using this system in clinical settings. Rapid and accurate diagnosis is critical for effective disease management and control, and developing this system can significantly improve our ability to respond to outbreaks of infectious diseases. [ FROM AUTHOR] Copyright of Bulletin of the Korean Chemical Society is the property of John Wiley & Sons, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

Design and Development of Nanoscale Aptasensors for Viral Diagnostics

Viral infection may be a serious threat for human beings. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a highly transmissible virus causing coronavirus disease 2019 (COVID-19) in humans and creating a universal pandemic outbreak. The current methods for detection of SARS-CoV-2 include real-time reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and loop-mediated isothermal amplification (LAMP). Though the methods are widely used for the diagnosis of COVID-19, they too have their limitations such as time-consuming process, sophisticated instrumental setup, which requires highly skilled personnel for operation, and prevalence of false positive/negative reports. Therefore, there is a pressing need to develop alternative tools such as point-of-care testing (POCT) devices to detect SARS-CoV-2 rapidly, accurately, and user-friendly. Here, the authors propose a one-step diagnostic method using aptamer-based sensing technology. The intended design of aptamer-based biosensors (also known as aptasensors) utilizes the optical properties of gold nanoparticles (AuNP) conjugated with angiotensin-converting enzyme-2 (ACE-2) aptamers targeting SARS-CoV-2 using lateral flow assay (LFA). This study leads to the development of portable nanoscale aptasensors for viral diagnostics. © 2022 by the authors.

SARS-CoV-2 evolved variants optimize binding to cellular glycocalyx.

Viral variants of concern continue to arise for SARS-CoV-2, potentially impacting both methods for detection and mechanisms of action. Here, we investigate the effect of an evolving spike positive charge in SARS-CoV-2 variants and subsequent interactions with heparan sulfate and the angiotensin converting enzyme 2 (ACE2) in the glycocalyx. We show that the positively charged Omicron variant evolved enhanced binding rates to the negatively charged glycocalyx. Moreover, we discover that while the Omicron spike-ACE2 affinity is comparable to that of the Delta variant, the Omicron spike interactions with heparan sulfate are significantly enhanced, giving rise to a ternary complex of spike-heparan sulfate-ACE2 with a large proportion of double-bound and triple-bound ACE2. Our findings suggest that SARS-CoV-2 variants evolve to be more dependent on heparan sulfate in viral attachment and infection. This discovery enables us to engineer a second-generation lateral-flow test strip that harnesses both heparin and ACE2 to reliably detect all variants of concern, including Omicron.

Specific lateral flow detection of isothermal nucleic acid amplicons for accurate point-of-care testing.

For point-of-care testing (POCT), coupling isothermal nucleic acid amplification schemes (e.g., recombinase polymerase amplification, RPA) with lateral flow assay (LFA) readout is an ideal platform, since such integration offers both high sensitivity and deployability. However, isothermal schemes typically suffers from non-specific amplification, which is difficult to be differentiated by LFA and thus results in false-positives. Here, we proposed an accurate POCT platform by specific recognition of target amplicons with peptide nucleic acid (PNA, assisted by T7 Exonuclease), which could be directly plugged into the existing RPA kits and commercial LFA test strips. With SARS-CoV-2 as the model, the proposed method (RPA-TeaPNA-LFA) efficiently eliminated the false-positives, exhibiting a lowest detection concentration of 6.7 copies/µL of RNA and 90 copies/µL of virus. Using dual-gene (orf1ab and N genes of SARS-CoV-2) as the targets, RPA-TeaPNA-LFA offered a high specificity (100%) and sensitivity (RT-PCR Ct < 31, 100%; Ct < 40, 71.4%), and is valuable for on-site screening or self-testing during isolation. In addition, the dual test lines in the test strips were successfully explored for simultaneous detection of SARS-CoV-2 and H1N1, showing great potential in response to future pathogen-based pandemics.

Detection and Diagnosis Technologies for SARS-CoV-2

Detection and diagnosis platforms play key roles in early warning, outbreak control and exit strategy for any pandemic, and they are especially pertinent for the Coronavirus disease 2019 (COVID-19) pandemic. The challenges posed by the speed and extent of severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) spread around the globe also offered unprecedented opportunities for the development and deployment of novel strategies and products - not only vaccines and therapeutics, but also diagnostics. This chapter provides a brief summary of the vast array of molecular, serological, cell-based and other diagnostic tools for the specific detection of SARS-CoV-2 infections and immune responses. The focus is on the principles and applications of each platform, while detailed protocols can be found in the cited references. © 2023 by World Scientific Publishing Co. Pte. Ltd.

Point-of-care COVID-19 diagnostics powered by lateral flow assay.

Since its first discovery in December 2019, the global coronavirus disease 2019 (COVID-19) pandemic caused by the novel coronavirus (SARS-CoV-2) has been posing a serious threat to human life and health. Diagnostic testing is critical for the control and management of the COVID-19 pandemic. In particular, diagnostic testing at the point of care (POC) has been widely accepted as part of the post restriction COVID-19 control strategy. Lateral flow assay (LFA) is a popular POC diagnostic platform that plays an important role in controlling the COVID-19 pandemic in industrialized countries and resource-limited settings. Numerous pioneering studies on the design and development of diverse LFA-based diagnostic technologies for the rapid diagnosis of COVID-19 have been done and reported by researchers. Hundreds of LFA-based diagnostic prototypes have sprung up, some of which have been developed into commercial test kits for the rapid diagnosis of COVID-19. In this review, we summarize the crucial role of rapid diagnostic tests using LFA in targeting SARS-CoV-2-specific RNA, antibodies, antigens, and whole virus. Then, we discuss the design principle and working mechanisms of these available LFA methods, emphasizing their clinical diagnostic efficiency. Ultimately, we elaborate the challenges of current LFA diagnostics for COVID-19 and highlight the need for continuous improvement in rapid diagnostic tests.

Recent Advances in Novel Lateral Flow Technologies for Detection of COVID-19.

The development of reliable and robust diagnostic tests is one of the most efficient methods to limit the spread of coronavirus disease 2019 (COVID-19), which is caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, most laboratory diagnostics for COVID-19, such as enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase-polymerase chain reaction (RT-PCR), are expensive, time-consuming, and require highly trained professional operators. On the other hand, the lateral flow immunoassay (LFIA) is a simpler, cheaper device that can be operated by unskilled personnel easily. Unfortunately, the current technique has some limitations, mainly inaccuracy in detection. This review article aims to highlight recent advances in novel lateral flow technologies for detecting SARS-CoV-2 as well as innovative approaches to achieve highly sensitive and specific point-of-care testing. Lastly, we discuss future perspectives on how smartphones and Artificial Intelligence (AI) can be integrated to revolutionize disease detection as well as disease control and surveillance.

Fluorophore-encapsulated nanobeads for on-site, rapid, and sensitive lateral flow assay.

Since December 2019, the rapid and sensitive detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a priority for public health. Although the lateral flow assay (LFA) sensor has emerged as a rapid and on-site SARS-CoV-2 detection technique, the conventional approach of using gold nanoparticles for the signaling probe had limitations in increasing the sensitivity of the sensor. Herein, our newly suggested methodology to improve the performance of the LFA system could amplify the sensor signal with a facile fabrication method by concentrating fluorescent organic molecules. A large Stokes shift fluorophore (single benzene) was encapsulated into polystyrene nanobeads to enhance the fluorescence intensity of the probe for LFA sensor, which was detected on the test line with a longpass filter under ultraviolet light irradiation. This approach provides comparatively high sensitivity with the limit of detection of 1 ng mL-1 for the SARS-CoV-2 spike protein and a fast detection process, which takes less than 20 min. Furthermore, our sensor showed higher performance than gold nanoparticle-based commercial rapid diagnostics test kits in clinical tests, proving that this approach is more suitable and reliable for the sensitive and rapid detection of viruses, bacteria, and other hazardous materials.

Development of A Rapid, Low-Cost Portable Detection Assay for Enterococci in Wastewater and Environmental Waters.

Waterborne diseases are known as a leading cause of illness and death in both developing and developed countries. Several pathogens can be present in contaminated water, particularly waters containing faecal material; however, routine monitoring of all pathogens is not currently possible. Enterococcus faecalis, which is present in the microflora of human and animals has been used as a faecal indicator in water due to its abundance in surface water and soil. Accurate and fast detection methods are critical for the effective monitoring of E. faecalis in the environment. Although conventional and current molecular detection techniques provide sufficient sensitivity, specificity and throughput, their use is hampered by the long waiting period (1-6 days) to obtain results, the need for expensive laboratory equipment, skilled personnel, and cold-chain storage. Therefore, this study aimed to develop a detection system for E. faecalis that would be simple, rapid, and low-cost, using an isothermal DNA amplification assay called recombinase polymerase amplification (RPA), integrated with a lateral flow assay (LFA). The assay was found to be 100% selective for E. faecalis and capable of detecting rates as low as 2.8 × 103 cells per 100 mL from water and wastewater, and 2.8 × 104 cells per 100 mL from saline water. The assay was completed in approximately 30 min using one constant temperature (38 °C). In addition, this study demonstrated the quantitation of E. faecalis using a lateral flow strip reader for the first time, enhancing the potential use of RPA assay for the enumeration of E. faecalis in wastewater and heavily contaminated environmental waters, surface water, and wastewater. However, the sensitivity of the RPA-LFA assay for the detection of E. faecalis in tap water, saline water and in wastewater was 10-1000 times lower than that of the Enterolert-E test, depending on the water quality. Nevertheless, with further improvements, this low-cost RPA-LFA may be suitable to be used at the point-of-need (PON) if conjugated with a rapid field-deployable DNA extraction method.

Evaluation of lateral flow and ELISA techniques for detecting IgG and IgM antibodies in COVID-19 cases in Türkiye.

Background: Antibody testing can complement molecular assays for detecting COVID-19. Aims: We evaluated the concurrence between lateral flow assay and enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Methods: The study was conducted at Kocaeli University, Türkiye. We used a lateral flow assay and ELISA to test serum samples from COVID-19 cases, confirmed by polymerase chain reaction assays (study group) and pre-pandemic stored serum samples (control group). We used Deming regression to evaluate the antibody measurements. Results: The study group included 100 COVID-19 cases, and the control group included pre-pandemic samples from 156 individuals. The lateral flow assay detected immunoglobulin M (IgM) and G (IgG) antibodies in 35 and 37 study group samples. ELISA detected IgM nucleocapsid (N) antibodies in 18 samples, and IgG (N) and IgG spike 1 (S1) antibodies in 31 and 29 samples, respectively. None of the techniques detected antibodies in the control samples. Strong correlations were found between lateral flow IgG (N+ receptor-binding domain + S1) and ELISA IgG (S) (r = 0.93, P < 0.01) and ELISA IgG (N) (r = 0.81, P < 0.01). Weaker correlations were seen between ELISA IgG S and IgG N (r = 0.79, P < 0.01) and lateral flow assay and ELISA IgM (N) (r = 0.70, P < 0.01). Conclusion: Lateral flow assay and ELISA techniques gave consistent results for IgG/IgM antibody measurements towards spike and nucleocapsid proteins, suggesting that both methods can be used to detect COVID-19 where access to molecular test kits is difficult.

Multiplexed lateral flow assay integrated with orthogonal CRISPR-Cas system for SARS-CoV-2 detection.

The development of field-deployable detection platform amenable for multiplexed genes testing will significantly improve the efficiency and reliability during point-of-care testing (POCT) applications. In this regard, an orthogonal CRISPR-Cas-mediated multiplexed lateral flow assay (designated as OC-MLFA) is proposed for SARS-CoV-2 genome detection. Taking the advantage of activation and cleavage preferences between Cas12a and Cas13a, orthogonal (two-independent-channel signal readout) CRISPR-Cas system is investigated. Lateral flow strips with two target lines are designed to accommodate the orthogonal CRISPR system. The interference between Cas12a and Cas13a channels can be effectively eliminated via the elaborate nucleic acids and lateral flow strips design. The high preamplification efficiency from reverse transcription recombinase polymerase amplification (RT-RPA) and Cas enzyme mediated trans-cleavage process bring the sensitivity of our OC-MLFA method to 10 copies per test (30 µL). Nasopharyngeal swab clinical samples with different cycle threshold (Ct) values according to the RT-PCR method were analyzed with the proposed OC-MLFA, during which 76 out of 76 detection accuracy was obtained. Featured with the multiplexed genes detection simultaneously in one reaction and colorimetric readout through single strip, the OC-MLFA we proposed herein ensures great accuracy and efficiency, which endows promising field-deployable POCT application feasibility.

Development of colloidal Gold nanoparticle based lateral-flow assay for rapid detection of SARS-CoV-2 showing enhanced sensitivity and specificity

To stop the spread of COVID-19 in this outbreak, diagnostic testing is essential. Quick diagnostic tests must be employed in this pandemic, which is brought on by the severe acute respiratory syndrome (SARS)-CoV-2 virus, to successfully treat and manage COVID-19. There are several problems with the present RT-PCR system that the lateral flow assay (LFA), a kind of clinically sensitive diagnostic test, may be able to fix, especially in low-and middle-income nations. Gold nanoparticle-(AuNP-LFA) is a practical method for detecting COVID-19 in basic hospitals and laboratories, particularly in emergency situations where many samples must be quickly examined. Safe, accurate, and non-toxic diagnostic tests must be employed during the pandemic, to successfully treat and manage COVID-19. Recombinant SARS-CoV-2 nucleocapsid monoclonal antibody was employed to detect COVID-19 antigens in the presence of patients to establish a fast LFA for COVID-19. Synthesis of colloidal gold particles and antibody colloidal gold conjugates was evaluated by using UV/Vis spectroscopy. A capture line made of anti-SARS-CoV-2 antibody was coated on nitrocellulose membrane. To create the control line, goat anti-mouse IgG monoclonal antibody was coated. On a polystyrene backing board, the immunochromatographic strip was constructed in the ideal order. Using ELISA as the standard procedure, the strips' sensitivity and specificity were assessed. The results' stability and repeatability were evaluated over a 9-month period. Colloidal gold nanoparticle-based LFAs created in this study can be employed for quicker and more accurate detection of SARS-CoV-2. © 2023 Singh, et al.

Sandwich mode lateral flow assay for point-of-care detecting SARS-CoV-2

The global corona virus disease 2019 (COVID-19) has been announced a pandemic outbreak, and has threatened human life and health seriously. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as its causative pathogen, is widely detected in the screening of COVID-19 patients, infected people and contaminated substances. Lateral flow assay (LFA) is a popular point-of-care detection method, possesses advantages of quick response, simple operation mode, portable device, and low cost. Based on the above advantages, LFA has been widely developed for detecting SARS-CoV-2. In this review, we summarized the articles about the sandwich mode LFA detecting SARS-CoV-2, classified according to the target detection objects indicating genes, nucleocapsid protein, spike protein, and specific antibodies of SARS-CoV-2. In each part, LFA is further classified and summarized according to different signal detection types. Additionally, the properties of the targets were introduced to clarify their detection significance. The review is expected to provide a helpful guide for LFA sensitization and marker selection of SARS-CoV-2. [Display omitted] • LFA as a simple user friendly tool is widely employed for SARS-CoV-2 detection. • Present review focus on latest developments in LFAs to detect SARS-CoV-2. • Sensitization strategies and marker properties are beneficial to further research. [ FROM AUTHOR]

Humoral immune response in COVID-19 patients and novel design of lateral flow assay strip for simultaneous rapid detection of IgA/IgM/ IgG antibodies against the SARS-CoV-2 virus

At the end of 2019, a novel coronavirus (CoV) appeared in Wuhan, China and has since spread to several countries and regions throughout the world. The disease caused by the novel CoV has been officially named CoV disease 2019 (COVID-19). This study provides additional data for the presence of anti-SARS-CoV-2 IgM and IgG antibodies in COVID-19 patients in Vietnam. The study also presents the development of a lateral flow immunoassay (LFA) strip for rapid simultaneous detection of the IgA/IgM/IgG antibodies against the SARS-CoV-2 virus in COVID-19 patients. The properties of the LFA test strip were evaluated by testing specimens from COVID-19 positive and negative patients confirmed by real-time PCR. Reproducibility and repeatability reached 100%. The LFA test strip did not show any cross-reactivity with 13 different pathogens and did not interfere with anticoagulants. The sensitivity and specificity of the LFA test strips were evaluated with 633 clinical samples and were found to be 91.06% and 98.74%, respectively. The Kappa statistics showed almost perfect agreement and correlation between our test strip and real-time PCR results (k coefficient = 0.902). From the obtained results, it could be suggested that the LFA test strip is a useful tool for rapid detection of antibodies against SARS-CoV-2 to accelerate epidemiological surveillance, to determine the situation of exposure to SARS-CoV-2, and to increase the diagnostic accuracy of the real-time PCR method for COVID-19. © 2023 Ngo, et al.

Hybridization Chain Reaction Lateral Flow Assays for Amplified Instrument-Free At-Home SARS-CoV-2 Testing.

The lateral flow assay format enables rapid, instrument-free, at-home testing for SARS-CoV-2. Due to the absence of signal amplification, this simplicity comes at a cost in sensitivity. Here, we enhance sensitivity by developing an amplified lateral flow assay that incorporates isothermal, enzyme-free signal amplification based on the mechanism of hybridization chain reaction (HCR). The simplicity of the user experience is maintained using a disposable 3-channel lateral flow device to automatically deliver reagents to the test region in three successive stages without user interaction. To perform a test, the user loads the sample, closes the device, and reads the result by eye after 60 min. Detecting gamma-irradiated SARS-CoV-2 virions in a mixture of saliva and extraction buffer, the current amplified HCR lateral flow assay achieves a limit of detection of 200 copies/µL using available antibodies to target the SARS-CoV-2 nucleocapsid protein. By comparison, five commercial unamplified lateral flow assays that use proprietary antibodies exhibit limits of detection of 500 copies/µL, 1000 copies/µL, 2000 copies/µL, 2000 copies/µL, and 20,000 copies/µL. By swapping out antibody probes to target different pathogens, amplified HCR lateral flow assays offer a platform for simple, rapid, and sensitive at-home testing for infectious diseases. As an alternative to viral protein detection, we further introduce an HCR lateral flow assay for viral RNA detection.

CRISPR-based point-of-care plant disease diagnostics.

The coupling of clustered regularly interspaced short palindromic repeats (CRISPR)-Cas RNA-programmable nucleases with nucleic acid detection platforms has brought radical changes to the field of disease diagnosis. Recently, Sánchez et al. developed a simple, rapid, highly sensitive, precise, and in-field deployable point-of-care (POC) and point-of-need (PON) molecular disease detection tool that can be used in diverse agricultural applications.

Development of fluorescent lateral flow immunoassay for SARS-CoV-2-specific IgM and IgG based on aggregation-induced emission carbon dots.

Understanding the dynamic changes in antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential for evaluating the effectiveness of the vaccine and the stage for the recovery of the COVID-19 disease. A rapid and accurate method for the detection of SARS-CoV-2-specific antibodies is still urgently needed. Here, we developed a novel fluorescent lateral flow immunoassay (LFA) platform for the detection of SARS-CoV-2-specific IgM and IgG by the aggregation-induced emission carbon dots conjugated with the SARS-CoV-2 spike protein (SSP). The aggregation-induced emission carbon dots (AIE-CDs) are one of the best prospect fluorescent probe materials for exhibiting high emission efficiency in both aggregate and solid states. The AIE-CDs were synthesized and displayed dual fluorescence emission, which provides a new perspective for the design of a high sensitivity testing system. In this work, the novel LFA platform adopted the AIE carbon dots, which are used to detect SARS-CoV-2-specific IgM and IgG conveniently. Furthermore, this sensor had a low LOD of 100 pg/ml. Therefore, this newly developed strategy has potential applications in the areas of public health for the advancement of clinical research.

Pressed Lateral Flow Assay Strips for Flow Delay-Induced Signal Enhancement in Lateral Flow Assay Strips.

This paper proposes that the signal intensity of a lateral flow assay (LFA) strip can be increased by pressing the top of the strip, effectively reducing its flow rate. The reduced flow rate allows more time for antigen-antibody interactions to occur, resulting in increased signal intensity and an improved detection limit. To assess the potential of the pressed LFA (pLFA) strip, C-reactive protein (CRP) diluted in phosphate-buffered saline (PBS) and serum is detected, affording signal enhancement and a lowered limit of detection. Additionally, to show that the signal enhancement by pressure-induced flow delay applies to existing LFA products, commercially available COVID-19 antigen test strips are pressed, and signal enhancement is observed. Lastly, we show that the signal intensity of COVID-19 LFA kits can be increased by approximately two-fold at maximum by applying pressure on top of the manufactured product. This study suggests that pressed LFA strips can be used to reduce the chances of determining ambiguous signals as false-negative results and can potentially improve the detection sensitivity. Supplementary Information: The online version contains supplementary material available at 10.1007/s13206-022-00085-w.

Current Advances in Paper-Based Biosensor Technologies for Rapid COVID-19 Diagnosis.

The global coronavirus disease 2019 (COVID-19) pandemic has had significant economic and social impacts on billions of people worldwide since severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in Wuhan, China, in November 2019. Although polymerase chain reaction (PCR)-based technology serves as a robust test to detect SARS-CoV-2 in patients with COVID-19, there is a high demand for cost-effective, rapid, comfortable, and accurate point-of-care diagnostic tests in medical facilities. This review introduces the SARS-CoV-2 viral structure and diagnostic biomarkers derived from viral components. A comprehensive introduction of a paper-based diagnostic platform, including detection mechanisms for various target biomarkers and a COVID-19 commercial kit is presented. Intrinsic limitations related to the poor performance of currently developed paper-based devices and unresolved issues are discussed. Furthermore, we provide insight into novel paper-based diagnostic platforms integrated with advanced technologies such as nanotechnology, aptamers, surface-enhanced Raman spectroscopy (SERS), and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas. Finally, we discuss the prospects for the development of highly sensitive, accurate, cost-effective, and easy-to-use point-of-care COVID-19 diagnostic methods.

Evaluation of a point of care lateral flow assay for antibody detection following SARS CoV-2 mRNA vaccine series.

BACKGROUND: Breakthrough cases of SARS-CoV-2 infection correlate with decreased antibody immunity following mRNA vaccination. Measuring kinetics of vaccine efficacy using traditional laboratory approaches is more expensive and can be impractical. In this study, we evaluated the diagnostic performance of a validated COVID-19 point-of-care lateral flow assay (LFA) kit in detecting post-vaccination antibody response. METHODS: We conducted a prospective cohort study of whole blood and plasma samples to evaluate the performance of a LFA in detecting SARS-CoV-2-specific antibodies following mRNA vaccination compared to enzyme-linked immunosorbent assays (ELISAs). Health care workers at 2 tertiary centers who completed an initial BNT162b2 (n = 103) or mRNA-1273 (n = 35) vaccine series were enrolled between June and August of 2021. We performed an exploratory analysis to correlate band strength and antibody concentration of LFAs and ELISAs respectively. RESULTS: When compared to the ELISA, LFA results showed similar test positivity for plasma samples (P = 0.55), but not for whole blood samples (P < 0.001). For whole blood samples on the LFA, antibody detection differed between BNT162b2 (68.9%, 95% CI: 59.1%-77.7%) and mRNA-1273 (100%, 95% CI: 90.0%-100%, P < 0.001) vaccines. Higher plasma antibody concentrations correlated with greater LFA sensitivity. Samples with thick LFA bands had higher antibody concentrations compared to samples having faint LFA bands (81.8 arbitrary unit [AU]/mL vs. 57.1 AU/mL, P < 0.01). CONCLUSIONS: The performance of a LFA in detecting SARS-CoV-2 antibodies was significantly better when plasma samples were used. The strength of label bands on the LFA may correlate with antibody concentration and could be a useful point-of-care monitoring tool for post-vaccine antibody status.