The rapid antibody test for COVID-19 developed by the US diagnostic and biopharmaceutical company Cellex receives the first Emergency Use Authorization (EUA) approval for marketing from the US FDA, announced the company.
The test allows to obtain results within 15-20 minutes after a drop of the sample including serum, plasma, or whole blood is placed into a well on a small cartridge. The test indicates the presence of antibodies- IgM, IgG, or both formed against the SARS-CoV-2 virus by forming lines on the device.
However, the issue warns that results from antibody testing should not be used as the sole basis to diagnose or exclude COVID-19 infection, as negative results do not rule out infection.
Negative results may also occur if antibodies might not have had enough time to form or the virus could have had a minor amino acid mutation in the epitope recognized by the antibodies screened for in the test. Similarly, false positives can occur due to cross-reactivity with antibodies from previous infections, such as from other coronaviruses, says the company.
“IgM antibodies are generally detectable several days after the initial infection, while IgG antibodies take longer. It’s not known how long COVID-19 antibodies persist after the infection has cleared,” the agency said.
As part of its authorization, the FDA stated that the test has not been formally approved by the agency. Currently, the testing is limited to Clinical Laboratory Improvement Amendments-certified labs.