[ad_1]
The coronavirus induces strong and long-lasting cellular immunity after infection, new research shows, suggesting that people are unlikely to quickly contract the disease again and increase the chances that vaccines will be effective.
“Our study is the first in the world to show that strong cellular immunity remains six months after infection in people who experienced mild / moderate or asymptomatic Covid-19,” said Professor Paul Moss of the University of Birmingham. Professor Moss heads the UK Coronavirus Immunology Consortium which studied 100 UK healthcare workers who were infected early in the Covid-19 pandemic.
The findings, which have not yet been peer-reviewed, are an encouraging sign for the development of vaccines that aim to induce immunity without causing disease, the researchers said. They also suggest that few people will be reinfected with the Sars-Cov-2 virus responsible for Covid-19 shortly after suffering a first infection.
The human immune response to viral infection is extremely complex and involves the production of both antibodies and cells, especially T cells, to fight the virus. Other research has shown that antibody levels often drop rapidly after Covid-19 patients have recovered.
In contrast, the results of the new study “show that T-cell responses may outlast the initial antibody response, which could have a significant impact on Covid vaccine development and immunity research.” said Shamez Ladhani, an epidemiologist at Public Health England and an author of the research.
“This is promising news,” said Fiona Watt, CEO of the Medical Research Council, which is co-funding the project. “If natural infection with the virus can elicit a robust T-cell response, this may mean that a vaccine could do the same.”
Antibodies, relatively small protein molecules, are much easier to detect and analyze in blood samples than much larger and more complex T cells, which is why Covid-19 researchers have studied more extensively.
The UK Coronavirus Immunology Consortium tested blood from 100 healthcare workers who tested positive for Sars-Cov-2 during March and April: 44 had no symptoms and 56 had mild or moderate respiratory symptoms, but none were ill enough enough to need hospital treatment.
All 100 blood samples had T cells that targeted a variety of proteins in Sars-Cov-2, including the key “spike protein” that the virus uses to enter human cells and that is a target of Covid vaccines. -19. In contrast, antibody levels in some people had dropped to undetectable levels within six months.
The size of the cellular response varied markedly between individuals. On average, it was 50 percent higher in people who had experienced symptoms than in those who were asymptomatic six months earlier.
More research is needed to find out if this increased cellular immunity would provide more protection against re-infection in people with more severe symptoms, Dr. Ladhani said. Asymptomatic people may be able to fight the virus without generating a large immune response, he added.
Some cases of people infected twice with Sars-Cov-2 have been reported, but the numbers are “reassuringly low” among tens of millions of Covid-19 cases, said Dr. Ladhani: “We would expect only a small minority of reinfected people. “
Eleanor Riley, a professor of immunology at the University of Edinburgh, who was not involved in the research, added: “This is all very good news and bodes well for the long term, both in terms of vaccine development and the possibility of protection. against reinfection “.
