Wed. Sep 28th, 2022
Extreme close up photo of gloved hands holding a test tube.
enlarge MAY 4, 2020: A health professional takes a blood sample on the first day of a free COVID-19 antibody testing event.

Following a flurry of fake coronavirus blood tests, the U.S. Food and Drug Administration announced Monday that testmakers must submit data within 10 days showing that their tests actually work — or risk being removed from the market.

The new requirement updates a lax policy the FDA announced on March 16 that prioritized providing “regulatory flexibility” so that these blood tests — also known as serology tests — can come to market quickly during the pandemic. That flexibility came at the cost of normal scientific scrutiny that ensures those tests meet 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. “We unfortunately see unscrupulous actors marketing fraudulent test kits and using the pandemic as an opportunity to capitalize on Americans’ fears.”

The serological tests are intended to detect antibodies against the new coronavirus, SARS-CoV-2. Antibodies are Y-shaped proteins that can circulate in the blood to recognize specific germs that the immune system has previously fought off. Antibodies generally do this by targeting features of a germ, such as the spiny proteins protruding from the SARS-CoV-2. If the germ reappears, those antibodies — made by specialized immune cells — can quickly recognize the invader and trigger an immune response to try to prevent reinfection.

So the presence of antibodies in a person’s blood only tells whether the immune system has encountered the germ in the past — it’s not used to diagnose new cases of COVID-19, the disease caused by SARS-CoV-2. There are separate diagnostic tests for this, which usually work by detecting genetic material from the virus itself.

Testing people for previous infections is especially helpful at the population level. It can help public health researchers understand how far the virus has spread, what proportion of infected people have asymptomatic or extremely mild cases, and the true death rate from the disease (which is generally calculated by the number of deaths below the number of infected people recover that.)

Test Limits

For better understood diseases, antibody tests can also help determine whether a person is likely to be immune to reinfection. That is, for some diseases, our immune system can make muscular antibodies that can completely prevent reinfection. So if a person tests positive for antibodies to a specific germ, that may mean they are protected against that disease. But not all antibodies are so protective. They may also become weak or diminish over time, possibly within a few months. For now, we don’t know enough about our own immune responses to SARS-CoV-2 to know whether antibodies to the virus are protective and, if so, for how long. That means if someone tests positive for SARS-CoV-2 antibodies, they may still be able to get COVID-19.

As such, testing for SARS-CoV-2 antibodies is largely an academic endeavor for now — trying to understand its spread, asymptomatic cases and death rate. It’s not yet for determining a person’s immunity, and it certainly isn’t for diagnosing new cases. For these reasons, in March, the FDA thought it would be safe to relax oversight of serology testing during the pandemic.

But since then, the market has been flooded with shoddy testing and false claims. “Some test developers have falsely claimed that their serology tests are FDA-approved or authorized. Others have falsely claimed that their tests can diagnose COVID-19 or are for home testing,” the FDA said. The agency also noted that “a number of commercial serology tests are inappropriately promoted, including for diagnostic use, or perform poorly based on an independent review by the [National Institutes of Health]†

The FDA said it has approved only 12 tests so far, but reviews for more than 200 others are in the works.

Now test makers must begin submitting data to the FDA, and the agency has set “specific performance threshold recommendations” for how many false positives and false negatives of any test are acceptable. The agency said it will “continue to take steps to properly balance assurances that an antibody test is accurate and reliable with timely access to such tests.”

By akfire1

Leave a Reply

Your email address will not be published.