FDA: Makers of coronavirus antibody checks should now present checks really work

Enlarge /. MAY 4, 2020: Health workers treat a blood sample on the first day of a free COVID-19 antibody test event.

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After a flood of fake coronavirus blood tests, the U.S. Food and Drug Administration announced on Monday that test manufacturers must provide data within 10 days that their tests actually work – or are at risk of being withdrawn from the market will.

The new requirement updates a lax policy that the FDA announced on March 16 that primarily provides "regulatory flexibility" to enable these blood tests – also called serology tests – to be launched quickly during the pandemic. This flexibility came at the expense of a normal scientific review, which ensures that these tests meet the standards for accuracy and reliability.

"In mid-March, it was critical for the FDA to provide regulatory flexibility to serology test developers given the nature of this public health emergency. However, flexibility never meant we would allow fraud," the FDA wrote in a policy update Monday . "Unfortunately, we see unscrupulous actors who market fraudulent test kits and use the pandemic as an opportunity to take advantage of American fear."

The serological tests are designed to detect antibodies against the new coronavirus SARS-CoV-2. Antibodies are Y-shaped proteins that can circulate in the blood to recognize certain germs that the immune system has previously warded off. Antibodies generally do this by examining a germ's signature characteristics, such as: B. the spiky proteins that protrude from the SARS-CoV-2. When the germ reappears, these antibodies – made by specialized immune cells – can quickly identify the intruder and trigger an immune response to prevent re-infection.

So the presence of antibodies in a person's blood only indicates whether the immune system has met the germ in the past – it is not used to diagnose new cases of COVID-19, the disease caused by SARS-CoV-2. There are separate diagnostic tests for this, in which genetic material from the virus itself is generally detected.

Testing people for past infections is mainly helpful at the population level. It can help public health researchers understand how widely the virus has spread, what percentage of those infected have asymptomatic or extremely mild cases, and what the actual death rate of the disease (which is generally based on the number of deaths under the Number of infected is calculated) recover.)

Test limits

With better understood diseases, antibody tests can also help determine if a person is likely to be immune to re-infection. That is, in some diseases, our immune system can produce beefy antibodies that can completely prevent re-infection. If a person tests positive for antibodies to a particular germ, it may mean that they are protected from the disease. But not all antibodies are so protective. They can also be weak or decrease over time – possibly within months. We currently do not know enough about our own immune responses against SARS-CoV-2 to know if and for how long antibodies protect against the virus. That is, if someone tests positive for SARS-CoV-2 antibodies, they may still get COVID-19.

Therefore, testing SARS-CoV-2 antibodies is largely an academic endeavor to try to understand the spread, asymptomatic cases, and death rate. It is not yet used to determine a person's immunity and certainly no new cases will be diagnosed. For these reasons, the FDA considered it safe in March to relax supervision of serological testing during the pandemic.

But since then, the market has been flooded with bad tests and false claims. “Some test developers have incorrectly claimed that their serological tests were approved or approved by the FDA. Others have incorrectly claimed that their tests can diagnose COVID-19 or that they are for home testing, ”said the FDA. The agency also found that "a significant number of commercial serology tests are advertised inappropriately, including for diagnostic purposes, or perform poorly due to an independent assessment by the (National Institutes of Health)".

The FDA said it has only approved 12 tests to date, but reviews for over 200 others are in progress.

Now test manufacturers need to start sending data to the FDA, and the agency has “specific performance threshold recommendations” that determine how many false positive and false negative results a test will accept. The agency said it would "continue to take steps to adequately balance the certainty that an antibody test is accurate, reliable, and has timely access to such tests."