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A Rapid, Multiplex Dual Reporter IgG and IgM SARS-CoV-2 Neutralization Assay for a Multiplexed Bead-Based Flow Analysis System
Published on: April 6, 2021
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Antigen concentration, viral load, and test performance for SARS-CoV-2 in multiple specimen types
Allison Golden1, Michelle Oliveira-Silva2, Hannah Slater1
1Diagnostics, PATH, Seattle, Washington, United States of America.
Plos One
|July 19, 2023
Summary
Rapid diagnostic tests (RDTs) for SARS-CoV-2 show varying performance based on specimen type. Nasal swabs offer better antigen detection than saliva, suggesting RDTs are more reliable with nasal samples.
Area of Science:
- Virology
- Infectious Diseases
- Diagnostic Technologies
Background:
- Rapid diagnostic tests (RDTs) are crucial for SARS-CoV-2 detection, but their performance varies with specimen type.
- Understanding the correlation between viral load and N-antigen concentration across different specimens is key to optimizing RDT clinical utility.
Purpose of the Study:
- To investigate the performance of RDTs across different specimen types (nasopharyngeal swab, anterior nares swab, saliva).
- To analyze the correlation between N-antigen concentration and viral load within and across these specimen types.
- To evaluate how antigen concentration influences RDT results and guides interpretation.
Main Methods:
- Prospective study of 214 close contacts of confirmed SARS-CoV-2 cases.
- Antigen concentration measured in nasopharyngeal swabs (NPS), anterior nares swabs (ANS), and saliva.
- RT-PCR performed on NPS and saliva; RDTs performed on ANS and saliva.
- Analysis of antigen concentration, viral load, and RDT results in relation to symptoms and vaccination status.
Main Results:
- Antigen concentration correlated well with viral load within the same specimen type, but not across different types.
- Antigen levels were higher in symptomatic cases and in nasal samples (NPS, ANS) compared to saliva.
- RDT results on ANS showed good correlation with RT-PCR on NPS, with antigen concentration aiding in discordant result interpretation.
Conclusions:
- Antigen dynamics in SARS-CoV-2 infection support the use of RDTs with nasal samples for better clinical sensitivity.
- Saliva RDTs require enhanced analytical sensitivity to match the performance of nasal RDTs due to lower antigen concentrations.
- RDT analytical limit-of-detection can predict population-level performance based on known antigen concentrations.
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