corona virus-Covid19

Overview of COVID-19 Serological Tests Interview with:

Abdi Ghaffari, Ph.D. Associate Professor (adjunct) Dept. of Pathology and Molecular Medicine Queen’s University

Dr. Ghaffari

Abdi Ghaffari, Ph.D.
Associate Professor (adjunct)
Dept. of Pathology and Molecular Medicine
Queen’s University What is the background for this study?

Response: SARS-CoV-2 virus has infected millions and changed our way of life by placing nearly 3 billion people under lockdown or some form of physical isolation. In the absence of a vaccine or reliable treatment, diagnostic testing must be a pillar of public health policy to control further spread of the virus and to guide gradual removal of lockdown measures.

COVID-19 antibody diagnostic tests are being increasingly used to assess the protective immunity status in the population. There are over 100 different COVID-19 antibody tests developed by companies worldwide in an effort to address this need. However, companies’ reported performance data are not always in line with the actual performance of these diagnostic tests in the real-world. In this work, we conducted a systemic review of independent studies (sponsored by academic or government institutions) that aimed to validate the performance of currently available COVID-19 antibody tests on the market. What are the main findings?

Response: In this study, we provide a brief overview of different types of COVID-19 antibody test and the role they can play in assessing immunity status in the population. We then reviewed independent performance data on 20 laboratory-based (ELISA and CLIA assays) and 42 Rapid Diagnostic tests (with point-of-care capacity) currently on the market.

We found significant variability in sensitivity (the ability of a test to detect the host antibody when it is truly present) between COVID-19 antibody tests, with only a small subset of the diagnostic tests achieving greater than 95% sensitivity and specificity (the ability to currently return a negative results). The top performing COVID-19 antibody tests (13 tests that achieved greater than 95% accuracy in independent validation studies) are highlighted in Table 1 of the paper. What should readers take away from your report?

Response: There are two types of COVID-19 diagnostic tests:

1) molecular (e.g., PCR to detect virus RNA) and

2) antibody test (to detect virus-specific antibodies in host blood).

Much of the focus has been on the molecular testing to detect the presence of the virus in suspected individuals. However, molecular tests are not useful in assessing protective immunity status in individuals with or without symptoms (not all infected people show COVID-19 symptoms or may have cleared the virus). Antibody tests must complement molecular testing to provide a more complete picture of COVID-19 infection and “herd immunity” in the population.

As manufacturer’s claims are not always in line with real-world data, our study identifies COVID-19 antibody tests with high level of performance required for large-scale testing of populations to assess immunity status. These finding suggests that massive technological effort to develop reliable COVID-19 antibody diagnostic tests have led successfully to the development of a number of reliable antibody tests that can help us in the fight against this pandemic.

Readers should also understand that “countries cannot fight this pandemic blindfolded; and should know where the infected cases are”, as quoted by Dr. Tedros Adhanom Ghebreyesus, Director-General of the World Health Organization. What recommendations do you have for future research as a result of this work? 

  1. As serological tests are in high demand, in part due to an increase in large-scale seroprevalence studies, it is imperative for national and regional governments to support coordinated efforts to independently validate antibody test performance.
  2. For national and regional government to partner with private industry to scale up manufacturing and production capacity of rapid diagnostic test (point-of-care capable).
  3. Continue the support for collaborative and coordinated research efforts to address the following key gaps in our knowledge of COVID-19 disease:
    1. Which specific host antibodies that can neutralize SARS-CoV-2 virus?
    2. How long does immunity against SARS-CoV-2 last? Are infected individuals susceptible to re-infection in future?
    3. What individuals have the highest potential of transmitting the virus? At what stage of the disease? 

Any disclosures?  The authors declare no conflict of interest and no financial affiliation with companies listed in the study.


Ghaffari, A.; Meurant, R.; Ardakani, A. COVID-19 Serological Tests: How Well Do They Actually Perform? Diagnostics 2020, 10, 453. 

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Last Updated on July 17, 2020 by Marie Benz MD FAAD