Natural immunity to coronavirus could be TWICE as common as experts thought, according to a study by Public Health England, millions have protective T cells from similar cold viruses
- Researchers find that 25 percent of the nearly 3,000 key workers have high T cell levels
- Antibody surveys consistently showed no more than 6 percent test positive
- One study found that no one with high T cell responses got Covid for the next four months
A quarter of the population may already be immune to Covid, as studies by health authorities show.
A study conducted by Public Health England found that T cells – an important part of the immune system – are present in far higher numbers than expected in people.
The investigation of 2,847 key workers from the NHS, police and fire department in June found that 25 percent of participants had a high proportion of T cells that detected Covid.
This is far higher than the results of antibody surveys, which consistently found no more than 6 percent of positive tests for Covid.
Research among 2,847 key workers from the NHS, the police and the fire department in June showed that 25 percent of the participants had a high percentage of T cells that detected Covid. An archive image is used above (file photo)
So far, much of the scientific community's attention has focused on antibodies that neutralize a virus before it enters the cells of the body. In comparison, T cells target and destroy cells that are already infected with the virus.
Crucially, none of the patients with high T-cell responses were infected with Covid in the next four months – which suggests that this part of the immune system is an effective protective factor.
They also found that only half of those who had high T cell responses had identifiable Covid antibodies.
Dr. Peter Wrighton-Smith of Oxford Immunotec, the company that developed the T-cell test, said, "The implication is that there is a population of people who are protected from Covid and are not covered by the antibody studies."
He emphasized that the people in the study all worked on the front lines – therefore, they were more likely to be exposed to Covid.
The researchers believe this could suggest two possibilities. One theory is that antibodies wear off very quickly after someone recovers from Covid – but T cells last longer.
Another reason is that people have immunity to similar coronaviruses – like those that cause colds – even if they have never been infected with Covid themselves.
Dr. Wrighton-Smith added, "We don't cover all cases with antibody surveys, so more people may be protected than we thought."
Dr. David Wyllie, Consultant Microbiologist at Public Health England and lead author of the study, said: “Four months into the study, 20 participants with lower T cell responses had developed Covid-19 compared to none in those with higher T cell responses.
"This suggests that people with higher numbers of T cells that recognize SARS-CoV-2 may have some protection from Covid-19, although more research is needed to confirm this."
So far, much of the scientific community's attention has focused on antibodies that neutralize a virus before it enters the cells of the body. In comparison, T cells target and destroy cells that are already infected with the virus
Professor Karol Sikora, a cancer expert at the University of Buckingham, was one of the first to highlight the importance of T cells early in the pandemic.
In a video posted on Twitter last night, he said, “This is really good news. This almost certainly means that the T cell response is innate – it is (triggered) by something that humans have been exposed to in the past.
“If Corona comes, they are not vulnerable.
“It suggests that more people are protected than estimates by antibodies, but many likely have residual immunity to Covid-19 from other infections as well.
“T cells have been overlooked for too long. This proves that this needs to change. "
Dr. However, Rupert Beale of the Francis Crick Institute in London said the problem may be related to the antibody tests used.
"About a quarter had highly reactive T cells, more than half of them had serological evidence of previous infection with tests that were about 70 percent sensitive – so only a very small proportion of adults (less than 10 percent, maybe much less)." than 10 percent) would be protected by an already existing T-cell immunity. "
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