CORE LABORATORY
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SARS-CoV-2 Slide Rule

Click or swipe through this interactive tool to see how different COVID-19 tests can be used to help evaluate and manage a patient at different times during the course of their infection.

ADD-132945-USA-EN

Click on the arrows to move the slider forward or backward

Click on the arrows to move the slider forward or backward

graph-key

TEST RESULTS

+
RNA
-
Antigen
-
IgM
-
IgG (SP)
-
IgG (NP)

Patient may be in the initial period of infection when antibodies are not yet produced or are under the limit of detection.1-11
Following vaccination, viral load and antigen, if present, will be low and likely not detected.14

graph-key

TEST RESULTS

+
RNA
+
Antigen
-
IgM
-
IgG (SP)
-
IgG (NP)

Individual has an active infection and has not developed an immune response.1-11
Following vaccination, viral load and antigen, if present, will be low and likely not detected.14

graph-key

TEST RESULTS

+
RNA
+
Antigen
+
IgM
-
IgG (SP)
-
IgG (NP)

Patient is in the active phase of infection and has started to develop an immune response with antibody production.1-11
Following vaccination, viral load and antigen, if present, will be low and likely not detected.14

graph-key

TEST RESULTS

+
RNA
+
Antigen
+
IgM
+
IgG (SP)
+
IgG (NP)

Patient is still in the active phase of the infection; immune response has progressed.1-11
Both IgM and IgG appear in vaccinated patients. IgG/IgM Nucleocapsid (NP) are only detected following attenuated whole virus vaccines and/or natural infections.15, 16, 17

graph-key

TEST RESULTS

+/-
RNA
+/-
Antigen
+
IgM
+
IgG (SP)
+
IgG (NP)

Patient may still be in the active phase of infection but RNA and Antigen may be negative. Specific IgM antibodies to SARS-CoV-2 may be detectable in COVID-19 patients during the symptomatic phase of the disease after RNA is no longer detectable.1-11
Both IgM and IgG appear in vaccinated patients. IgG/IgM Nucleocapsid (NP) are only detected following attenuated whole virus vaccines and/or natural infections.15, 16, 17

graph-key

TEST RESULTS

-
RNA
-
Antigen
+
IgM
+
IgG (SP)
+
IgG (NP)

Patient may be in the late or recovery stages of infection or RNA false negative.1-11
Both IgM and IgG appear in vaccinated patients. IgG/IgM Nucleocapsid (NP) are only detected following attenuated whole virus vaccines and/or natural infections.15, 16, 17

graph-key

TEST RESULTS

-
RNA
-
Antigen
-
IgM
+
IgG (SP)
+/-
IgG (NP)

Antibodies may be detected following a natural infection or vaccination.1-13
IgG Spike (SP) is detected and IgG Nucleocapsid (NP) is not detected following a spike protein based vaccine.
IgG Nucleocapsid (NP) and Spike (SP) would be positive following natural infection or attenuated
whole virus vaccine.15, 16, 17 IgG Nucleocapsid (NP) has a shorter half life than IgG Spike (SP).18

Antibody titers for convalescent plasma require high titer levels of neutralizing antibody. Titer levels can be defined independently and are measurable for IgG Nucleocapsid and Spike RBD assays.19

SARS-CoV-2 Viral/Antibody Infection Interpretation1-17

TEST RESULTS GENERAL INTERPRETATION**
RNA Antigen IgM IgG(SP) IgG(NP)
+ - - - -
Patient may be in the initial period of infection when antibodies are not yet produced or are under the limit of detection
+ + + - -
Patient is in the active phase of infection and has started to develop an immune response with antibody production
-/+ -/+ + - -
Patient may be in the early stage of infection. RNA or antigen result may be undetectable due to timing or specimen collection technique
+ - + + +
Patient is likely in the latter stage of infection, particularly when PCR cycle counts are high which suggest residual RNA remnants
- - + + +
Patient is likely in the late or recovery stages of a natural infection or vaccinated with an attenuated whole virus vaccine
- - + + -
Antibodies detected following a natural infection or a spike protein-based vaccination
- - - + +
Patient has recovered or has been infected in the past or vaccinated with an attenuated whole virus vaccine
- - - + -
Antibodies detected following a natural infection or a spike protein-based vaccination

**Test results must be considered with other clinical data available to the clinician.

Click on an individual row to
view the General Interpretation

References

  1. Current performance of COVID-19 test methods and devices and proposed performance criteria, Working document of Commission services. European Commission, April 16, 2020.
  2. Tan W, Lu Y, Zhang J, et al. Viral Kinetics and Antibody Responses in Patients with COVID-19. medRxiv; 2020. DOI: 10.1101/2020.03.24.20042382.
  3. Guo L, Ren L, Yang S, et al. Profiling Early Humoral Response to Diagnose Novel Coronavirus Disease (COVID-19). Clin Infect Dis. 2020;71(15):778-785. doi:10.1093/cid/ciaa310
  4. Long, Q., Liu, B., Deng, H. et al. Antibody responses to SARS-CoV-2 in patients with COVID-19. Nat Med 26, 845–848 (2020). https://doi.org/10.1038/s41591-020-0897-1
  5. Zhao, J., Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019. Clinical infectious diseases an official publication of the Infectious Diseases Society of America, ciaa344C
  6. Xiao AT, Gao C, Zhang S. Profile of specific antibodies to SARSCoV-2: the first report. J Infect 2020. doi:10.1016/j.jinf.2020.03.012
  7. Chaplin DD. Overview of the immune response. J Allergy Clin Immunol. 2010;125(2 Suppl 2):S3-S23. doi:10.1016/j.jaci.2009.12.980
  8. Rokni M, Ghasemi V, Tavakoli Z. Immune responses and pathogenesis of SARS-CoV-2 during an outbreak in Iran: Comparison with SARS and MERS. Rev Med Virol. 2020;30(3):e2107. doi:10.1002/rmv.2107
  9. K.K-W. To et al. Temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by SARS-CoV-2: an observational cohort study. Lancet Infectious Diseases 2020. https://doi.org/10.1016/S1473-3099(20)30196-1
  10. Lumley SF, O’Donnell D, Stroesser NE, et al. Antibody status and incidence of SARS-CoV-2 infection in health care workers. N. England Journal of Medicine. DOI: 10.1056/NEJMoa2034545.
  11. SARS-CoV-2 Immunity: Review and Applications to Phase 3 Vaccine Candidates. Lancet 2020;Oct 13.
  12. Burbelo PD, Riedo FX, Morishima C, et al. Detection of Nucleocapsid Antibody to SARS-CoV-2 is More Sensitive than Antibody to Spike Protein in COVID-19 Patients. medRxiv; 2020. DOI: 10.1101/2020.04.20.20071423.
  13. Amanat F, Krammer F. SARS-CoV-2 Vaccines Status Report. Immunity. 2020;52(4)583-589. doi10.1016j.immuni.2020.03.007
  14. Levine-Tiefenbrun, M., Yelin, I., Katz, R. et al. Initial report of decreased SARS-CoV-2 viral load after inoculation with the BNT162b2 vaccine. Nat Med (2021). https://doi.org/10.1038/s41591-021-01316-7
  15. Narasimhan M, Mahimainathan L, Araj E, et al. Clinical evaluation of the Abbott Alinity SARS-CoV-2 spike-specific quantitative IgG and IgM assays among infected, recovered, and vaccinated groups. J Clin Microbiol 2021;00388-21. doi:10.1128/JCM.00388-21
  16. Wu, J., Liang, B., Chen, C. et al. SARS-CoV-2 infection induces sustained humoral immune responses in convalescent patients following symptomatic COVID-19. Nat Commun 12, 1813 (2021). https://doi.org/10.1038/s41467-021-22034-1
  17. Keech, Cheryl (2020). Phase 1-2 Trial of a SARS-CoV-2 Recombinant Spike Protein Nanoparticle Vaccine. The New England journal of medicine. 383. 10.1056/NEJMoa2026920.
  18. Jan Van Elslande, Lien Gruwier, Lode Godderis, Pieter Vermeersch, Estimated half-life of SARS-CoV-2 anti-spike antibodies more than double the half-life of anti-nucleocapsid antibodies in healthcare workers, Clinical Infectious Diseases, 2021;, ciab219, https://doi.org/10.1093/cid/ciab219
  19. Convalescent Plasma EUA Letter of Authorization, March 9, 2021.

 

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