Study Finds Three-quarters of People Living with a Coronavirus Victim May Develop ‘Silent’ Immunity Not Detected by Antibody Tests
- The number that Covid-19 has suffered may have been greatly underestimated
- Tests look for antibodies in the blood instead of the body’s ‘memory’ T cells
- 6 out of 8 people living with Covid-19 patients tested negative for antibodies
- They had suffered from Covid-19 with mild symptoms, they found evidence of T-cell immunity
A study has shown that up to three-quarters of people in a home can develop ‘silent’ immunity to the coronavirus when one is infected.
The number Covid-19 has suffered may have been vastly underestimated because tests look for specific antibodies in the blood instead of the body’s ‘memory’ T cells that fight infection, experts say.
Six of eight of those living with someone who tested positive for Covid-19 showed negative results when tested for antibodies to the coronavirus in their blood, the scientists found.
Study has shown that up to three-quarters of people in a home can develop ‘silent’ immunity to coronavirus when one is infected (stock image)
But when experts analyzed their blood samples to determine the immunity of T cells, part of the body’s deep defenses against infections, from the white blood cells in the bone marrow, they found that they had, in fact, suffered from Covid-19 with mild symptoms.
Some patients’ immune systems appear to be “divided” by their response to the virus, so those without blood antibodies react to a deeper level with a T-cell response, immunology experts said last night. This raises the possibility of new controls for the coronavirus that work to detect T cells similar to tuberculosis tests, with the potential for a laboratory to process hundreds of patients and obtain effective results in two days.
It is currently estimated that up to 10 percent of the population may have immunity to the virus, based on blood antibody tests, which detect antibodies generated by B cells in the blood.
T cells are the body’s great weapon, released by white blood cells from the bone marrow to kill viruses when the immune system needs more help.
The latest study at the University Hospital of Strasbourg in France examined seven families because their crown blood tests were unusual.
“Our results suggest that epidemiological data based solely on the detection of antibodies to SARS-CoV-2 may lead to a substantial underestimation of exposure to the virus,” said researcher Professor Samira Fafi-Kremer.
The study involves a small sample and has not yet been peer-reviewed, but immunologists are closely considering it. Professor Danny Altmann, of Imperial College and the British Society for Immunology, said there was mounting evidence that Covid-19 immunity seemed unusual, as some people showed immunity only from ‘memory’ T cells.
A normal response to a virus would be that antibodies in the blood, from B cells, are also present.
It means that a large number of people infected and with mild symptoms may be reacting differently to the virus that leaves them immune ‘silently’, because they cannot be diagnosed as exposed to Covid-19 by current tests.
The number Covid-19 suffered from may have been vastly underestimated because tests look for specific antibodies in the blood rather than the body’s ‘memory’ T cells that fight infection, experts say (stock image)
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