The first test for a T-cell response to the virus behind Covid-19 received emergency approval for use in the United States, creating another option for people to find out if they had the disease.
Adaptive Biotechnologies, a Seattle-based biotechnology company, worked with Microsoft to create the blood test, which may be more accurate than some of the antibody tests available on the market.
In addition to creating antibodies, the immune system produces T cells in response to an infection. T cells are white blood cells that can directly kill infected cells or help B cells to stimulate the production of antibodies.
Lance Baldo, medical director at Adaptive, said that T cells are important because they have a “very long memory” and appear to remain in the body for at least six to nine months. Considering that the pandemic has only been around for a year, they can last even longer.
Baldo said this could be particularly useful for people who suffer from “long Covid” – with symptoms that persist for months – who may not have had a positive test at the time. This can help shape your care and, in the U.S., it can influence the amount insurers will pay.
“You have these people with long-term Covid, they’re not sure if they were really infected, their antibodies are definitely gone, they’re not going to have a positive PCR [diagnostic test], and they’re just calling us to say, ‘I want to know if three months, six months, nine months ago, I really had the coronavirus,’ ”he said.
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Adaptive’s lab tests, which are now available at concierge clinics, can now be ordered by doctors in the United States.
The Food and Drug Administration’s authorization for emergency use comes after a study showed that T cells can play an important role in the immune response to new variants. Researchers at the La Jolla Institute for Immunology and the University of California said they found that T-cell responses in those vaccinated, or previously infected, were as robust as the variants first identified in the UK, Brazil, South Africa and California.
Adaptive says his research, which has not yet been peer-reviewed, has shown that his test detects 97 percent of people who have had the disease, compared to antibody tests ranging from 77 to 97 percent. The proportion of false negatives was less than 1 percent.
There hasn’t been enough research yet to find out if the discovery of these T cells means that people are immune to the Sars-Cov-2 virus. But Adaptive hopes that the patients who take the test will opt for the research, which will allow the company to monitor them and see if any develop Covid-19.
Adaptive is also working with vaccine developers, who have so far focused on whether their injections elicit an antibody response, to see if they can get a T-cell reaction as well.
Microsoft machine learning tools helped Adaptive to map the body’s immune system. Adaptive also plans to create tests for the response of T cells to other infectious diseases, such as Lyme disease and autoimmune diseases.