The FDA has authorized its first COVID-19 antibody test designed to be used on-site at the point of care—such as within doctors' offices, urgent care centers and emergency rooms—as opposed to having samples shipped and tested within a central laboratory.
The fingerstick blood test, which operates using only a lined strip similar to a pregnancy test, is designed to provide results for two types of coronavirus antibodies within 15 minutes.
While manufactured by Assure Tech based in Hangzhou, China, the company is represented in the U.S. by Azure Biotech, an in vitro diagnostic company in Houston. The testing strip was previously authorized by the FDA in July, for use in certified labs with samples drawn from a vein.
The lateral flow test searches for IgG and IgM antibodies that target the coronavirus’s spike protein, used to unlock and enter human cells, as well as the protein that encapsulates the virus’s genetic code. It is only available by prescription and is performed by a healthcare professional.
In June, the test was independently evaluated by researchers at the National Cancer Institute’s Frederick National Laboratory for Cancer Research—part of an interagency initiative to ensure the accuracy of antibody tests—who compared its results against frozen blood samples taken from people before the pandemic who later went on to catch the disease.
They found that between the two types of antibodies, the test had a combined sensitivity of 100%, resulting in no false-negative results and a specificity of 98.8%, or a false-positive rate of 1.2%.
A separate study of fingerstick blood samples showed a specificity of 100%, as well as 100% sensitivity when used at least 15 days after a person first showed COVID-19 symptoms.
“Authorizing point-of-care serology tests will enable more timely and convenient results for individuals who want to understand if they have previously been infected with the virus that causes COVID-19,” FDA Commissioner Stephen Hahn, M.D., said in an agency statement.
“Until today, serology test samples were generally only able to be evaluated in a central lab, which can be time consuming and use additional resources to transport samples and run the test,” Hahn added, with nearly 50 antibody tests receiving an agency green light so far.
“As more and more point-of-care serology tests are authorized, they will help conserve those resources and may help reduce processing time for other types of COVID-19 tests, as less time is spent on serology tests,” he said.
However, it is still unknown how long antibodies persist in the bloodstream following an infection, as well as which specific kinds of antibodies offer the most protection from the disease. At the moment, serology testing cannot tell whether a person carries immunity, but only if they’ve had a prior or recent exposure to the virus that causes COVID-19.
In addition, the FDA said that among populations with a low prevalence of the disease, “even high-performing antibody tests may produce as many or more false results as true results because the likelihood of finding someone who has been infected is very small.”