SARS-CoV-2 Rapid Antigen Test

Reliable, rapid chromatographic immunoassay for the qualitative detection of specific antigens of SARS-CoV-2

SARS-CoV-2 Rapid Antigen Test
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An aid in identifying individuals infected by SARS-CoV-21

The SARS-CoV-2 Rapid Antigen Test is a reliable, rapid chromatopgraphic immunoassay for the qualitative detection of specific antigens of SARS-CoV-2 present in nasopharyngeal or combined nasopharyngeal/oropharyngeal samples.

This test is an aid in detecting antigen from the SARS-CoV-2 virus in individuals suspected of COVID-19. This product is strictly intended for professional use in laboratory and Point of Care environment.

SARS-CoV-2: An overview of virus structure, transmission and detection

 

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is an enveloped, single-stranded RNA virus of the family Coronaviridae. Coronaviruses share structural similarities and are composed of 16 nonstructural proteins and 4 structural proteins: spike (S), envelope (E), membrane (M), and nucleocapsid (N). Coronaviruses cause diseases with symptoms ranging from those of a mild common cold to more severe ones such as Coronavirus Disease 2019 (COVID-19) caused by SARS-CoV-2.

SARS-CoV-2 is transmitted from person-to-person primarily via respiratory droplets, while indirect transmission through contaminated surfaces is also possible.2,3 The virus accesses host cells via the angiotensin-converting enzyme 2 (ACE2) receptor, which is most abundant in the lungs.4,5

The incubation period for COVID-19 ranges from 2 - 14 days following exposure, with most cases showing symptoms approximately 4 - 5 days after exposure.2,6 The spectrum of symptomatic infection ranges from mild (fever, cough, fatigue, loss of smell and taste, shortness of breath) to critical.7,8 While most symptomatic cases are not severe, severe illness occurs predominantly in adults with advanced age or underlying medical comorbidities and requires intensive care. Acute respiratory distress syndrome (ARDS) is a major complication in patients with severe disease. Critical cases are characterized by e.g., respiratory failure, shock and/or multiple organ dysfunction, or failure.7,9

Upon infection with SARS-CoV-2, the host mounts an immune response against the virus, including production of specific antibodies against viral antigens. Both IgM and IgG have been detected as early as day 5 after symptom onset.10,11 Median seroconversion has been observed at day 10 - 13 for IgM and day 12 - 14 for IgG,12-14 while maximum levels have been reported at week 2 - 3 for IgM, week 3 - 6 for IgG and week 2 for total antibody.10-16 Whereas IgM seems to vanish around week 6 - 7,17,18 high IgG seropositivity is seen at that time.10,17,18 While IgM is typically the major antibody class secreted to blood in the early stages of a primary antibody response, levels and chronological order of IgM and IgG antibody appearance seem to be highly variable for SARS-CoV-2. Anti-SARS-CoV-2 IgM and IgG often appear simultaneously, and some cases have been reported where IgG appears before IgM, limiting its diagnostic utility.11,12,14,19,20 

After infection or vaccination, the binding strength of antibodies to antigens increases over time - a process called affinity maturation.21 High-affinity antibodies can elicit neutralization by recognizing and binding specific viral epitopes.22,23 In SARS-CoV-2 infection, antibodies targeting both the spike and nucleocapsid proteins, which correlate with a strong neutralizing response, are formed as early as day 9 onwards, suggesting seroconversion may lead to protection for at least a limited time.19,24

Coronavirus illustration
  • Nucleocapsid protein (N)
  • Envelope protein (E)
  • Spike protein (S)
  • Membrane glycoprotein (M)
  • RNA
The benefit of having a SARS-CoV-2 antigen test available

The SARS-CoV-2 virus causes respiratory tract infection. It is transmitted mainly via respiratory droplets after close contact, and primary viral replication is presumed to occur in mucosal epithelium of the upper respiratory tract (nasal cavity and pharynx). At these locations viral load peaks within the first week after symptom onset, and then declines.

A SARS-CoV-2 antigen test detects the presence of the SARS-CoV-2 virus from part of the upper respiratory tract swab specimens by identifying a nucleoprotein that is carried by the virus. The test identifies current infection during the acute phase of COVID-19, while the virus is still present in large quantities in the respiratory tract.

 

Features and benefits of the SARS-CoV-2 Rapid Antigen Test

 

Besides laboratory PCR testing, antigen assays can also be offered as rapid testing in near-patient settings. The SARS-CoV-2 Rapid Antigen Test is a rapid chromatographic immunoassay intended for the qualitative detection of specific antigens of SARS‑CoV‑2 present in nasopharyngeal or combined nasopharyngeal/oropharyngeal samples. This test is intended to detect antigen from the SARS‑CoV‑2 virus in individuals suspected of COVID‑19. This product is strictly intended for professional use in laboratory and Point of Care environments.1  Similar to laboratory instruments, it detects a SARS-CoV-2 antigen, the nucleoprotein. It can therefore be used to assess whether a person is infected with SARS-CoV-2 by providing a qualitative result showing coloured bands indicating the presence of SARS-CoV-2 antigens.

The SARS-CoV-2 Rapid Antigen Test enables fast decision making e.g. whether patients need to be put in quarantine, reducing the risk of further spreading. In addition to that it allows for screening of individuals after confirmed exposure to a SARS-CoV-2 infected person or individuals at risk of exposure such as healthcare workers.

The SARS-CoV-2 Rapid Antigen Test allows for decentralized testing at the point of care and helps to expand the range and quantity of direct virus testing into otherwise inaccessible locations. Rapid point of care testing can sometimes be the only viable option if lab testing is not sufficiently available. In addition to that, the SARS-CoV-2 Rapid Antigen Test is an instrument free test, allowing testing in rural/ low-infrastructure areas.

 

The benefits of the SARS-CoV-2 Rapid Antigen Test in short

 

  • Getting a quick result within 15-30 minutes – no need for a follow-up appointment to discuss the result
  • Easy handling which does not require specific training
  • No instrument required
  • Allowing decentralized testing or access to testing in areas where laboratory testing is not available

Testing the quick and easy way - testing process for the SARS-CoV-2 Rapid Antigen Test¹

Testing process

1. Collecting a sample (nasopharyngeal swab)*

Insert a sterile swab into the nostril of the patient and then rotate the swab 3-4 times against the nasopharyngeal surface. Withdraw the swab from the nasal cavity.

*When collecting a combined NP/OP sample be sure to follow the procedures described in the Instructions for Use.

Testing process

2a. Preparing a sample

Insert the swab into an extraction buffer tube. While squeezing the buffer tube, stir the swab more than 5 times.

Testing process

2b. Preparing a sample

Remove the swab while squeezing the sides of the tube to extract the liquid from the swab.

Testing process

2c. Preparing a sample

Press the nozzle cap tightly onto the tube. Continue with 3a. Performing a test.

Testing process

3a. Performing a test

Place the test device on a flat surface and apply 3 drops of extracted sample in a 90° angle to the specimen well of the test device.

Testing process

3b. Performing a test

Read the test result at 15 to 30 min.

Warning: Risk of incorrect results. Do not read the test result after 30 min.

Testing process

4. Interpreting results

A colored line appears in the top section of the result window to show that the test is working properly. This is the control line (C). Even if the control line is faint, the test should be considered to have been performed properly. If no control line is visible the test is invalid.

In case of a positive result, a colored line appears in the lower section of the result window. This is the test line (T). Even if the test line is very faint or not uniform, the test result should be interpreted as a positive result.

product image of SARS-CoV-2 Rapid Antigen Test
Test kit information

The kit is ready for use and contains all equipment needed to perform a test.

The following components are needed for a test and included in the kit:

  • Test device (individually in a foil pouch with desiccant)
  • Extraction buffer tube
  • Nozzle cap
  • Sterile swab
  • Film (can be attached to the test device when performing outdoor testing) 
  • Instructions for use
  • Quick Reference Guide
SARS-CoV-2-Antigen-test-kit

SARS-CoV-2 Rapid Antigen Test characteristics

  • Assay format

    Lateral flow test / immunochromatographic

  • Instrument

    No

  • Testing time

    15-30 minutes

  • Specificity

    99.2%

     

  • Sensitivity

    95.5% (Ct value ≤ 30)

     

  • Antigen

    N

  • Sample material

    Nasopharyngeal or combined nasopharyngeal/oropharyngeal

  • Reagents

    mAb anti-COVID19 antibody, mAb anti-Chicken IgY, mAb anti-COVID-19 antibody‑gold conjugate, Purified chicken IgY‑gold conjugate

References

  1. SARS-CoV-2 Rapid Antigen Test Package Insert 2021-12, V 4.0.
  2. Chan, J.F., Yuan, S., Kok, K.H., To, K.K., Chu, H., Yang, J. et al.-Lancet. 395, 514–523.-2020- El (v1.0)
  3. Kampf, G., Todt, D., Pfaender, S., Steinmann, E.-J Hosp Infect. 104(3), 246–251.-2020- Elecsys Ant (v1.0)
  4. Letko, M., Marzi, A., Munster, V. (2020).-Nat Microbiol. 1–8. doi:10.1038/s41564-020-0688-y.-2020- (v1.0)
  5. Hoffmann, M., Kleine-Weber, H., Schroeder, S. et al.-[published online ahead of print, 2020 Mar 4]. (v1.0)
  6. Lauer SA et al.-Ann Intern Med 2020;172(9):577-82-The Incubation Period of COVID-19 (v1.0)
  7. Rothe, C et al-N Engl J Med 2020;382(10):970-971-2020-Lab Infectious Diseases Respiratory tract infec (v1.0)
  8. Kupferschmidt K-Science. https://www.sciencemag.org/news/2020/02/paper-non symptomatic-patienttrans (v1.0)
  9. Bai Y et al-JAMA 2020;323(14):1406-1407-2020-Lab Infectious Diseases Respiratory tract infections Co (v1.0)
  10. Liu, W. et al. (2020). J Clin Microbiol. 58(6), e00461-2. 
  11. To, K. et al. (2020). Lancet Infect Dis. 20(5), 565-74. 
  12. Long, Q. et al. (2020). medRxiv. https://doi.org/10.1101/2020.03.18.20038018. 
  13. Lou, B. et al. (2020). Eur Resp J. https://doi.org/10.1183/13993003.00763-2020. 
  14. Zhao, J. et al. (2020). Clin Infect Dis. pii: ciaa344. https://doi.org/10.1093/cid/ciaa344. 
  15. Zhang, B. et al. (2020). medRxiv. https://doi.org/10.1101/2020.03.12.20035048. 
  16. Wölfel, R. et al. (2020). Nature. 581, 465-469. 
  17. Xiao, D.A.T. et al. (2020). J Infect. 81(1), 147-178. 
  18. Tan, W. et al. (2020). medRxiv. https://doi.org/10.1101/2020.03.24.20042382. 
  19. Okba, N. et al. (2020). medRxiv. https://doi.org/10.1101/2020.03.18.20038059. 
  20. Alberts, B. et al. (2002). Molecular Biology of the Cell. 4th edition. New York: Garland Science. B Cells and Antibodies. Available from: https://www.ncbi.nlm.nih.gov/books/NBK26884/ 
  21. Klasse, P.J. (2016). Expert Rev Vaccines 15(3), 295-311. 
  22. Payne, S. (2017). Viruses: Chapter 6 - Immunity and Resistance to Viruses, Editor(s): Susan Payne, Academic Press, Pages 61-71, ISBN 9780128031094. 
  23. Iwasaki, A. and Yang, Y. (2020). Nat Rev Immunol. https://doi.org/10.1038/ s41577-020-0321-6. 
  24. Amanat, F. et al. (2020). Nat Med. https://doi.org/10.1038/s41591-020-0913-5.