Three-quarters of people living with a coronavirus patient can develop ‘silent’ immunity that is not detected by antibody testing, research shows
- The number that Covid-19 has incurred 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 have tested negative for antibodies
- They had contracted Covid-19 with mild symptoms, discovered T cell immunity tests
A study has shown that up to three-quarters of people in a household can develop “silent” coronavirus immunity.
The number that Covid-19 has suffered may be hugely underestimated because tests look for specific antibodies in the blood rather than the body’s ‘memory’ T cells that fight infection, experts say.
Six out of eight of those living with someone who tested positive for Covid-19 showed negative results when testing for coronavirus antibodies in their blood, scientists found.
Up to three-quarters of people in a household can develop ‘silent’ coronavirus immunity if one is infected, study shows (stock image)
The drop in the daily death toll creates hope that the virus is on its way
It was hoped that the coronavirus will now completely recede because no new deaths were recorded in London, Scotland, Wales and Northern Ireland yesterday.
In total, there were only 16 deaths in the UK, bringing the total to 44,236 since the start of the pandemic.
Aside from June 22, when only 15 deaths were recorded, it was the lowest daily toll since the closure in March and the first without any death in any of the three devolved countries.
The zero digit in London is in stark contrast to the peak of the pandemic, when more than 100 died in the capital every day.
Northwest and southwestern England also had no new fatalities. Those who died in England were 42 to 93 years old and all had underlying health problems. Yesterday’s figures also showed that 352 more people tested positive for Covid-19, bringing the total number of UK infections to 285,768.
The number of daily hospital admissions fell to a few figures in most areas after peaking at 3,199 on March 31.
These figures also contrast sharply with the 883 hospital admissions in London on March 29, shortly after the closure began, and 776 in the Midlands on March 31.
The total number of 47 fell below 100 for the first time since the start of data collection.
Ten cases in the North East of England and Yorkshire and eleven in the Midlands only marked regions with double hospitalizations.
But when experts tested their blood samples for T cell immunity – part of the body’s deep defenses against infection, from white blood cells in the bone marrow – they found they had actually contracted Covid-19 with mild symptoms.
Some patients’ immune systems appear to be “split” by their response to the virus, so those without antibodies in their blood respond at a deeper level with a T cell response, immunology experts said last night. This raises the prospect of new controls for coronavirus that work to detect T cells in a similar way to tuberculosis tests – with the ability for one laboratory to process hundreds of patients and achieve effective results within 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, that detect antibodies generated by blood B cells.
T cells are the body’s major weapon – it is released from the white blood cells in the bone marrow to kill viruses when the immune system needs more help.
In the latest study from the University Hospital of Strasbourg in France, seven families were examined because their corona blood tests were unusual.
“Our results suggest that epidemiological data based only on detection of SARS-CoV-2 antibodies may lead to a substantial underestimation of the exposure to the virus,” said Professor Samira Fafi-Kremer, researcher.
The study is a small sample and has yet to be peer-reviewed, but is closely considered by immunologists. Professor Danny Altmann of Imperial College and the British Society for Immunology said there was increasing evidence that Covid-19’s immunity looked unusual, as some people showed immunity through ‘memory’ T cells only.
A normal response to a virus would be if there are also antibodies in the blood – from B cells.
It means that a large number of infected people with mild symptoms react differently to the virus, keeping them ‘silently’ immune, since they cannot be determined to have been exposed to Covid-19 by current tests.
The number that Covid-19 has suffered may be hugely 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)