The immune response of people who have had symptoms is stronger. The presence of antibodies persisting for at least six months was demonstrated in a British study.
Posted today at 07:35
“Six months after contracting SARS-CoV-2, the blood of people who had mild, moderate or asymptomatic Covid-19 still contained immune cells that recognize the virus”, according to a new study revealed by the American site Medical News Today.
The internal medical review indicates that “confirmed cases of people having contracted the infection again remain extremely rare. This is despite the evidence that the number of antibodies to the virus in the blood of most people drops sharply after contracting a mild or asymptomatic infection. ”
The new research suggests that people who get the infection again may be rare because helper T cells, a type of immune cell, continue to protect most people from the virus for at least 6 months. Medical News Today explains the immune process in this article: “When they recognize a virus, helper T cells recruit other immune cells to make antibodies or kill infected cells.”
“Although our results give us cautious optimism about the strength and duration of immunity generated after infection with SARS CoV-2, this is only one piece of the puzzle,” says one. the two leaders of the study, Professor Paul Moss, specialist in hematology at the University of Birmingham in the United Kingdom, interviewed by the American site. We still have a lot to learn before we fully understand how immunity to Covid-19 works, ”he adds.
Current research does not provide direct evidence that the T cells scientists have identified will protect people from further infection. The study reported on by Medical News Today has not yet been published by a validating scientific journal but is available online on the bioRxiv website. Carried out between March and April 2020, it concerns 100 people who had recently recovered from Covid-19. Their symptoms were mild or moderate, or they were asymptomatic, and none of them required hospitalization. The oldest participant was 65 and the youngest 22, while 77 were female. They donated blood samples once a month, which allowed researchers to track the changing levels of antibodies targeting three different viral proteins.
“After six months, all of the participants had helper T cells in their blood that responded to the virus. One of the main ways in which cells responded was by production of IL-2, an immune signaling molecule especially important for fighting viral infections. Compared to people who did not have symptoms, the T cell responses of those who did have symptoms were 50% stronger, ”the study concludes.
According to the authors, higher cellular immunity may give people who have had symptoms better protection against the virus coming back in the future.
However, “it is also possible that the quality of the T cell response at the time of initial infection [chez les patients asymptomatiques] was sufficient to provide clinical protection. The relative sensitivity of patients with asymptomatic baseline disease to episodes of reinfection, whether clinically silent or symptomatic, should therefore be assessed over time ”.
The strength of T cell responses to the three different viral proteins correlated with the peak levels of the respective antibodies to these proteins over the previous six months. This suggests that these two branches of the immune system – the antibody-producing cells and the T cells – were collaborating in the response, says Professor Paul Morgan, director of the Institute for Systems Immunity Research at the University of Cardiff in the UK.
Posted today at 07:35