Serology Testing Is Critical in Overcoming the COVID-19 Pandemic—Now and in the Future

Role of Serology Tests in COVID-19

Serology tests for COVID-19 use a blood sample to identify antibodies to the virus (SARS-CoV-2).1 The presence of antibodies to SARS-CoV-2 in the blood indicates the patient, whether symptomatic or asymptomatic, had an immune response to the virus.

Serology tests play an important role throughout the patient care pathway and are vital for the management and surveillance of the virus. They are critical in determining the full scope of the disease, combating the pandemic, and rebuilding public confidence.

Recognizing the critical need for rapid and accurate diagnostic testing, we now have available a total antibody test - the SARS-CoV-2 Total assay* which detects both IgM and the longer-lasting IgG antibodies in blood to help provide a clearer picture of infection progression.

Monitoring, Therapy, and Follow-up

Serology tests play a critical role in patient management. Unlike viral RNA, which is not detectable after recovery from infection, antibodies to SARS-CoV-2 may remain in the blood indefinitely and be detected in patients who have recovered from the virus or unknowingly carried it.1,2 When immunity is better understood, serology tests may also be able to detect immunity in exposed individuals and populations. As the pandemic evolves, this capability will be extremely valuable in surveillance of the disease and in the event of future outbreaks.2,3

More specifically, serology testing can:

  • Help identify patients with resolving/resolved infections and thereby offer insight into the virus’s prevalence within populations, including infections that are/were mild or asymptomatic.
  • Potentially detect immunity in COVID-19–recovered individuals, which could allow people to return to work/society and contribute to economic activity.
  • Potentially detect immunity in individuals such as healthcare providers, allowing them to continue their efforts against COVID-19 and possibly avoid unnecessary quarantine.
  • Aid in the assessment of vaccination response.

Not all antibody tests are created equal

High quality, extensive reach and targeting the right protein are all essential to ensure we effectively manage the threat of COVID-19

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The Clinical Utility of SARS-CoV-2 Antibody Assays6

Serology AssayAntigen TargetSurveillance of general population4Acute settingContact tracing (known exposures traced within 1-3 weeks)Recovered Infection4Vaccinated with potential vaccine that targets S1 RBDPotential Immunity Assessment7
TotalS1 RBDHighly preferredHighly preferredHighly preferredAcceptable AlternateAcceptable AlternateCould be used
IgGS1 RBDHighly preferredAcceptable AlternateAcceptable AlternateHighly preferredHighly preferredHighly preferred
TotalNHighly preferredHighly preferredHighly preferredAcceptable AlternateMay not be appropriate for this applicationMay not be appropriate for this application
IgGNHighly preferredAcceptable Alternate5Acceptable Alternate6Highly preferredMay not be appropriate for this applicationMay not be appropriate for this application



4. If test specificity is >99.5% and if all types of antibodies persist equally.
5. Data limited on how IgG (N) compares to Total (N) for early detection when using highly sensitive and specific assays.
6. Based on available current data that supports some S and specifically some S1 RBD antibodies as associated with neutralization but no similar data for N. Detection of N does not directly indicate if (or at what levels) S1 RBD or other potentially protective spike antibody may be present.
7. At this time, it is unknown for how long antibodies persist following infection and if the presence of antibodies confers protective immunity.

*This test has not been FDA cleared or approved. This test has been authorized by FDA under an EUA for use by authorized laboratories. This test has been authorized only for detecting the presence of antibodies against SARS-CoV-2, not for any other viruses or pathogens. This test is only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of in vitro diagnostics for detection and/or diagnosis of COVID-19 under Section 564(b)(1) of the Act, 21 U.S.C. § 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner. Product availability may vary by country and is subject to regulatory requirements.

Immunity with resolved infection has yet to be established; additional data is necessary to confirm or refute.