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. 2025 May 28;15(11):1362.
doi: 10.3390/diagnostics15111362.

Comparative Analysis of RT-PCR and a Colloidal Gold Immunochromatographic Assay for SARS-CoV-2 Detection

Hui Li  1 , Dakai Liu  1 , Qiang Zhou  2 , George D Rodriguez  3 , Harlan Pietz  1   4 , Vishnu Singh  1 , Eric Konadu  1 , Keither K James  1 , Calvin Lui  1 , Mingyu Shao  1 , Junyu Chen  1 , Andrew Schreiner  1 , Carl Urban  5 , James Truong  5 , Nishant Prasad  5 , William Harry Rodgers  1   6
Affiliations

Comparative Analysis of RT-PCR and a Colloidal Gold Immunochromatographic Assay for SARS-CoV-2 Detection

Hui Li et al. Diagnostics (Basel). .

Abstract

Background/Objectives: The COVID-19 pandemic has highlighted the urgent need for rapid, accurate, and accessible diagnostic testing to effectively manage and contain the spread of SARS-CoV-2. RT-PCR is widely recognized as the gold standard for SARS-CoV-2 detection due to its high sensitivity and specificity. However, RT-PCR testing requires specialized laboratory equipment, highly trained personnel, and extended processing times, which limits its feasibility for large-scale screening and point-of-care applications. This study aims to systematically evaluate the diagnostic performance of RT-PCR and a colloidal gold immunochromatographic assay (GICA). Methods: By comparing these two methods, we seek to determine a GICA's effectiveness as a complementary or alternative diagnostic tool, particularly in resource-limited settings and scenarios requiring rapid, large-scale testing. We assessed the following key clinical parameters: sensitivity, specificity, NPV, PPV, and accuracy. Additionally, we investigated the correlation between GICA signal intensity and RT-PCR Ct values using regression analysis, receiver operating characteristic curve analysis, and the calculated area under the curve. Results: Our findings indicate that while RT-PCR exhibits superior sensitivity, GICA results demonstrate a strong correlation with RT-PCR results and provide a rapid, cost-effective alternative for SARS-CoV-2 detection. Unlike RT-PCR, which requires extensive resources and prolonged turnaround times, a GICA delivers results within 20 min, making it a viable option for decentralized testing and real-time public health interventions. Conclusions: These results suggest that a GICA can serve as a complementary diagnostic tool alongside RT-PCR, particularly in resource-limited settings and high-throughput screening scenarios. By integrating GICAs into broader testing strategies, healthcare systems can enhance early detection efforts, improve accessibility to diagnostics, and strengthen pandemic response measures.

Keywords: COVID-19; SARS-CoV-2; colloidal gold immunochromatographic assay; cycle threshold; point of care; reverse transcription polymerase chain reaction.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
The intensity of the reaction line is used to class antigen levels into five distinct grades.
Figure 2
Figure 2
Comparison of RT-PCR Ct values and GICA readings.
Figure 3
Figure 3
The regression analysis of Ct values and GICA readings indicates a strong negative correlation between the two variables.
Figure 4
Figure 4
Receiver operating characteristic of the GICA method. The AUC was approximately 0.859.
See this image and copyright information in PMC

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