A small UK study has found that “cellular immunity” to the pandemic SARS-CoV-2 virus is present after six months in people who had gentle or asymptomatic Covid-19 infections – suggesting they might have some level of protection for no less than that time.
Scientists presenting the findings, from 100 non-hospitalised Covid-19 patients in Britain, said they were “reassuring” but did not intent people cannot in infrequent cases be infected twice with the disease.
“While our findings cause us to be cautiously optimistic approximately the strength and length of immunity generated after SARS-CoV-2 infection, this is only one piece of the puzzle,” said Paul Moss, a professor of haematology at Britain’s Birmingham University who co-led the study.
“There is still a lot for us memorize before we have a full understanding of how immunity to Covid-19 works.”
The study, which has not yet been peer-reviewed by other experts but was once published online on bioRvix, analysed the blood of 100 patients six months after they had had either gentle or asymptomatic Covid-19. It found that while one of the crucial patients’ antibody levels had dropped, their T-cell response – another key a part of the immune system – remained robust.
“(Our) early results show that T-cell responses may live longer than the initial antibody response,” said Shamez Ladhani, a consultant epidemiologist at Public Health England who co-led the work.
The study also found the size of T-cell response differed, and was once substantially higher in people who had had symptomatic Covid-19 than those who had no symptoms when infected.
The researchers said this could be interpreted in two ways: It is imaginable that higher cellular immunity might give better protection against re-infection in people who had symptoms, or equally, that asymptomatic patients are better in a position to fight off the virus without the wish to generate a large immune response.
Experts indirectly involved with the study said its findings were important and would add to a growing body of knowledge approximately potential protective immunity to Covid-19.
“These results supply reassurance that, even though the titre of antibody to SARS-CoV-2 can fall below detectable levels inside a couple of months of infection, a degree of immunity to the virus is also maintained,” said Charles Bangham, chair of immunology at Imperial College London.
“On the other hand, the critical question remains: do these persistent T-cells supply efficient protection against re-infection?”
While more than 46 million people worldwide have been infected with Covid-19, confirmed cases of re-infection are so far very infrequent.
(This story has been published from a wire agency feed without modifications to the text.)
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