Enter search term

Why serological antibody testing is important for COVID-19 and how to use it

Oct 27, 2020

The importance of serological antibody testing for COVID-19 and how it’s being used today

 Antibody testing provides valuable information to help stop the spread of the virus.


The fight against SARS-CoV-2, the novel coronavirus causing the COVID-19 pandemic, requires multiple tools. While nucleic acid tests that detect the SARS-CoV-2 RNA genome are commonly used to detect if someone has an active COVID-19 infection, they cannot detect past exposure to SARS-CoV-2. Antibody tests can provide valuable information on potential immunity by testing for specific patient antibodies made against SARS-CoV-2 that commonly become detectable 1-3 weeks after COVID-19 symptom onset.  In particular, IgG antibody levels are known to contribute to longer-term immune memory to help in response to future infections by the same pathogen. While our knowledge around COVID-19 continues to evolve with numerous studies underway, antibody testing is useful in multiple situations as outlined below.


When and how are serological antibody tests used today?

  • SARS-CoV-2 population level seroprevalence studies.1
    If you are a public health official or community leader who wants to gain a better understanding of the number of infected individuals in the population to help determine a true case fatality rate 
  • Screening of recovered COVD-19 patients for convalescent plasma donation therapy.2,3,4 
    If you are screening recovered COVID-19 patients for the presence of anti-SARS-CoV-2 antibodies to determine eligibility of donors' serum for COVID-19 convalescent serum/plasma therapy for treatment of acutely ill patients. 
  • Monitoring immune responses to COVID-19 vaccine candidates.
    If you are conducting a clinical trial and need to assess a candidate’s immune status as part of the inclusion/exclusion criteria.  Or, perhaps your trial requires that you monitor immune responses during the trial to understand the vaccine efficacy. 
  • Researching the gaps in our understanding of SARS-CoV-2 and immunity. 
    If you are a researcher studying the SARS-CoV-2 immune response, including length of potential immunity, and identifying any potential antibody responses that correlate with protection from SARS-CoV-2. 
  • Identifying asymptomatic SARS-CoV-2 carriers.
    If you are conducting contact tracing using RT-PCR, serology tests can act as a complement particularly in the case of a false negative RT-PCR result to help identify those that have had contact with the virus to help reduce the spread of the virus.

As we learn more about SARS-CoV-2 related immunity, even more applications for serology tests could become evident. 


The importance of finding the right test!

If you are conducting studies similar to those above or have clients who are, antibody testing can complement your current testing methods and expand your offering. 


What’s important to know about the test you choose?

  • Sensitivity and scalability.
    ELISA is a robust, sensitive method and scalable to your laboratory needs. 
  • High specificity.  
    The use of recombinant antigens provides specific SARS-CoV-2 targets. 
  • Minimal cross-reactivity.
    Reduces false positives. 
  • Independently validated.
    Adds confidence to the strict criteria labs require for SARS-CoV-2 serology testing.​​


Do you know about ZEUS’s unique dual antigen approach?

The ZEUS ELISA SARS-CoV-2 IgG Test and Total Antibody Systems utilize a combination of recombinant spike protein 1 receptor binding domain (S1-RBD) and recombinant nucleoprotein (N-protein) as the antibody capture antigens. ZEUS’s dual antigen approach is unique as it provides the benefits of the nucleoprotein, which is highly immunogenic and abundant, with the spike protein (S1-RBD), which has a high affinity for neutralizing antibodies.


What SARS-CoV-2 antibody tests does ZEUS currently offer?

  •  ZEUS ELISA™ SARS-Cov-2 IgG Test System – FDA Emergency Use Authorization (EUA) received 
  • ZEUS ELISA™ SARS-CoV-2 Total Antibody (IgG, IgM, IgA) Test System – Validated and FDA EUA submission currently in review


The ZEUS ELISA SARS-CoV-2- IgG Antibody Test System has been granted Emergency Use Authorization (EUA) by the U.S. Food and Drug Administration (FDA) as a diagnostic test for the qualitative detection of IgG antibodies to the SARS-CoV-2 virus in human serum and plasma and is intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2, indicating recent or prior infection. The ZEUS ELISA SARS-CoV-2 IgG Test System is authorized for use either manually or on the Dynex Agility® Automated ELISA System.

The Dynex Agility® Automated ELISA System offers optimal high throughput and takes advantage of the SmartKit™ Gold packaging, providing the ability to fully automate the procedure from sample to result in a throughput meeting all laboratory requirements. The new test system also includes our proprietary SAVe Diluent, a unique component which changes color when serum or plasma is added, ensuring no well is missed!


Why use ZEUS ELISA SARS-CoV-2 antibody assays?

  • ZEUS dual antigen approach allows for optimal sensitivity and specificity 
  • Fast and scalable for your laboratory needs   
  • Flexible options 
  • Fully compliant with FDA EUA guidance 
  • Highly specific to reduce cross reactivity to other naturally circulating viruses


Test with Confidence. Test with ZEUS.

Get ZEUS test solutions in your lab. Order today!

For more information, please visit our website or contact our sales team.



The ZEUS Scientific Family


FDA EUA Disclaimer: This test has been authorized only for the presence of IgG antibodies against SARS-CoV-2, not for any other viruses or pathogens. This test has been authorized by FDA under an EUA for use by authorized laboratories. This test has not been FDA cleared or approved; 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 Food, Drug and Cosmetic Act, 21 U.S.C. § 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner.



  1. CDC: Large-scale Geographic Seroprevalence Surveys 
  2. FDA Issues Emergency Use Authorization for Convalescent Plasma as Potential Promising COVID–19 Treatment, Another Achievement in Administration’s Fight Against Pandemic
  3. Montelongo-Jauregui D et al. Convalescent serum therapy for COVID-19: A 19th century remedy for a 21st century disease. PLOS Pathogens August 12, 2020
  4. FDA 2020: Recommendations for investigational COVID-19 convalescent plasma. Washington, DC.
  5. Madore, D. V. et al., Utilization of serologic assays to support efficacy of vaccines in nonclinical and clinical trials: meeting at the crossroads. Vaccine 28, 4539–4547 (2010).


Back Share