More than 118 million people have contracted COVID-19, according to figures collected since the illness was first found in China in late 2019. But these are just the people who tested positive. About a year ago, there weren’t enough tests to go around, and even those who qualified might have had a hard time getting tested.
The antibody tests that followed were not good enough to confirm past infections. The scientific community soon discovered that antibodies would disappear in some patients after a few months, prompting worries about waning COVID-19 immunity. More in-depth immunity studies followed, proving that COVID-19 survivors would still show strong coronavirus-specific B and T cells (white blood cells), even when antibodies became undetectable. Those memory cells could effectively spearhead another fight against the virus during future infections. But testing for B and T cells isn’t simple or cheap.
A year later, the FDA issued an Emergency Use Authorization (EUA) for the Adaptive Biotechnologies T-Detect COVID Test. The new test would confirm a COVID-19 infection in people who suspect they survived the illness, including asymptomatic cases and people suffering from “Long COVID” without having ever been officially diagnosed with COVID-19. The test could also help with future immunity studies, including vaccine-induced immunity.
Adaptive partnered with Microsoft to develop the test. T-Detect relies on artificial intelligence from Microsoft to analyze T cells and determine whether white blood cells specific to the coronavirus are present in the bloodstream of people who suspect they’ve been infected. The immune system reacts to all microorganisms that infect the body, creating memory cells for the various pathogens it encounters. The same thing happens after vaccination. Different T cell types might be roaming the body at any given time; that’s why these tests have to identify the white blood cells that can recognize SARS-CoV-2 upon reinfection.
The test costs $150, according to the company’s website. The procedure involves drawing blood from patients, and additional costs are involved. But T-Detect could finally provide clear answers and peace of mind to people who never had the chance to get a test for COVID-19 last year and people with negative antibody tests.
A positive T-Detect result would mean a person still has COVID-19 immunity. The T cells would remember the virus, and they could mount an immediate response. The white blood cells can destroy infected cells and signal B cells to mass-produce a new wave of antibodies that can neutralize the virus.
By measuring T cell levels, scientists can determine how long COVID-19 immunity lasts. The test might also be used to measure the T cell response following vaccination. Repeated testing could reveal how long T cells are present in the blood after vaccination. In turn, this could help health officials determine how often people should receive booster shots.
Positive tests could also help confirm Long COVID cases in patients who never got a PCR test. Long COVID a chronic version of COVID-19 where survivors continue to exhibit symptoms after clearing the virus. Knowing with absolute certainty that a person suffers from this COVID-19 complication might be critical for future treatment options.
A positive T-Detect result would appear at least seven days after infection. A negative test would not exclude an acute illness, the FDA explains. Results should be used in combination with a clinical examination.
Testing is currently limited to Adaptive laboratories, so the T-Detect test isn’t a quick at-home test that anyone could do — the video at the end of the post explains how coronavirus-specific T cells are identified. More information about the T-Detect test is available on the official product pages at this link.
