US Lab Announces Production Of Millions Of Antibody Tests, But FDA’s “Relaxed Policy” A Concern

Antibody tests can determine whther a person has previously been infected by the SARS-CoV-2 virus (yellow). NIAID-RML/Flickr (CC BY 2.0)

Katy Pallister 16 Apr 2020, 17:48

Yesterday, Abbott Laboratories, an Illinois-based medical device and health care company, launched their third Covid-19 test: a laboratory-based antibody blood test that can identify if a person has had the novel coronavirus. Although their latest test is yet to be approved by the US Food and Drug Administration (FDA), Abbott have been allowed to market it under the “relaxed” rules announced by the FDA last month.

Aiming to distribute 4 million tests by the end of April, ramping up to 20 million per month in the US in June, the company is one of the largest to enter the US antibody test market.

There are two kinds of tests available for the SARS-CoV-2 virus: molecular testing and antibody testing. Molecular testing can determine whether a patient currently has an active infection, generally using a swab from a person’s airways to find any presence of viral material.

However, antibody testing (also known as serology testing), looks at the blood of an individual to determine the presence of antibodies – proteins developed by the body’s immune system in response to an infection. Therefore, this kind of testing can determine whether an individual was previously infected, information that will play a key role going forward in our fight against Covid-19.

“Antibody testing has the potential to unlock a lot of unknowns about this novel virus,” John Hackett, divisional vice president of Applied Research and Technology, Diagnostics, Abbott, said in a statement. “Having tests that can work in different healthcare settings is critical to our understanding of the virus and to helping give healthcare providers answers they need about their patients.”

Abbott’s test helps to detect the IgG antibody to SARS-CoV-2, produced by the body in the late stages of infection, one of the two types of antibodies that researchers will be looking for (the other being IgM). Both antibodies can remain detectable for months after a person has recovered, offering a look back into the patient's immune system history.

Whilst antibody testing can help to measure the impact of public health efforts and guide a response to Covid-19, concerns have been raised over the reliability of those tests on the market in regards to their potential to give false-negative or false-positive results.

“We now have at least 90 tests on the market, and we don’t know about the accuracy of the results,” Kelly Wroblewski, director of infectious disease programs, at the Association of Public Health Laboratories (APHL), told USA Today. “Having many inaccurate tests is worse than having no tests at all.”

At the time of writing, three antibody tests have been approved under the FDA’s emergency use pathway. One of which, manufactured by Cellex, has a reported sensitivity (the rate at which the test correctly identifies people who have the condition being tested for) of 93.8 percent, and a specificity (the rate at which the test correctly identifies people who don’t have the condition) of 95.6 percent.

According to reports in CNN and USA Today, the FDA have confirmed that they will start reviewing the performance of antibody tests in light of accuracy concerns, in conjunction with other organizations.

“I am concerned that some of the antibody tests that are on the market that haven't gone through the FDA scientific review may not be as accurate as we'd like them to be,” FDA Commissioner Dr Stephen Hahn told NBC’s “Meet the Press” on Sunday.

“I can assure the American people that what we're doing is using data and science to look at those tests to make sure that they're valid, they're accurate, and they're reproducible.”

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