The COVID-19 crisis has focused attention on immunoassays. Immunoassays have been used in clinical laboratory medicine since the 1960s and are indispensable tools in clinical diagnostics. Immunoassays are tests that are based on the binding of antibodies to antigens to identify the presence of a substance (an analyte). There has been a great opportunity for immunoassay companies to produce serology-based tests for COVID-19. Serology tests are important to better quantify the number of cases of COVID-19. Kalorama covers the market for immunoassays in its The Worldwide Market for In Vitro Diagnostic Tests, 12th Edtion:

A wide range of types of immunoassays is used to measure proteins (including antibodies), hormones, drugs, and other analytes. Fully automated immunoassay systems are now found in clinical laboratories. COVID-19 tests that can be used to identify whether individuals have been exposed to the virus by looking at the immune response have been developed. In order to meet an increased demand for clinical testing, the FDA opened the emergency use authorization (EUA) process to high-complexity CLIA labs on February 28, 2020 creating a new pathway for regulated assay development in the COVID-19 emergency.

A number of companies worldwide have received clearance or are developing tests including:

  • Epitope Diagnostics offers the EDI Novel COVID-19 IgG ELISA Kit. The EDI Novel Coronavirus COVID-19 IgG and IgM assays utilize a microplate-based enzyme linked immunoassay (ELISA) technique, an established technology and industry standard in diagnostics. The assay procedure is simple to perform with a two-step plate wash with a total incubation time of less than 2 hours for up to 91 samples per plate. Both IgG and IgM kits have already been used for clinical testing at multiple sites in China. The test is CE marked.
  • Medakit offers a COVID-19 IgM/IgG Rapid Test POC lateral flow immunoassay. It can be used for rapid screening of carriers of the virus that are symptomatic or asymptomatic. The test is CE marked.
  • Eagle Biosciences offers the Coronavirus COVID-19 IgM ELISA Assay Kit. It is used for the qualitative detection of novel coronavirus infected pneumonia cases, suspected clustering cases, and other new coronaviruses in serum samples (COVID-19) through measurement of the COVID-19 IgM antibody. It is a serological plate-based assay technique designed for detecting and quantifying substances such as peptides, proteins, antibodies and hormones. It is CE marked.
  • BD and BioMedomics launched a rapid serology test to detect exposure to COVID-19 in March 2020. This is a rapid test provided at the point of care providing results in just 15 minutes. The test analyzes blood, serum or plasma samples for the presence of immunoglobulin M (IgM) and Immunoglobulin G (IgG) antibodies associated with the coronavirus (SARS-CoV-2). IgM provides the first line of defense during viral infections, followed by the generation of adaptive, high-affinity IgG responses for long-term immunity and immunological memory. The detection of COVID-19 IgM antibodies tends to indicate a recent exposure to COVID-19, and detection of COVID-19 IgG antibodies indicates a later stage of infection. The test is completed in four, simple steps. First, blood is collected through normal blood collection devices such as the BD Microtainer Contact-Activated Lancet. A few drops of blood are then transferred to the test cartridge, followed by two to three drops of a buffer. The results can be read in 15 minutes, similar to how over-the-counter pregnancy tests show multiple lines for positive results and a single line for negative results. As of May 21, 2020, the test was removed from the FDA EUA list.
  • Gold Standard Diagnostics Group participants have developed COVID-19 ELISA assays including COVID-19 IgG, IgM and IGA tests.
  • Ortho-Clinical Diagnostics offers its ELISAQ test that detects IGG and is designed to be used with VITROS Immunodiagnostic Products and the VITROS 3600 system. It was approved for EUA by FDA.
  • Roche launched its Elecsys Anti-SARS-CoV-2 serology test to detect antibodies in people that have been exposed to COVID-19. The Elecsys Anti-SARS-CoV-2 immunoassay is an in vitro test, using human serum and plasma drawn from a blood sample, to detect antibodies and determine the body’s immune reaction to SARS-CoV-2.

These are among scores of immunoassay products released that can detect COVID-19 immune response.