Two studies show that antibodies generated in other diseases are effective against Covid-19. This is the principle of cross-immunity.
What if cross immunity is the key to coronavirus? An American study, published in the scientific journal Cell, suggests that there may be more people immune to Covid-19 than the latest studies suggest.
This study first shows that all infected people have produced CD4 + cells which stimulate the production of antibodies to Covid-19. A reassuring point on the resistance of antibodies and which eliminates the risk of reinfection.
Antibodies effective in healthy patients
Most importantly, the study shows that this immune response to cell production is also present in individuals who have not been infected with Covid-19. The study authors examined blood samples taken between 2015 and 2018, before the arrival of Covid-19. Between 40% and 60% of these samples contained these CD4 + cells, which are particularly reactive against Covid-19. This suggests the hypothesis of cross immunity.
The confirmation came recently from 2 nice studies in Celle et Nature (it’s something other than Raoult’s excuse …) and there must be plenty of others: there would be immunity crossed with others virus.
– Yonathan Freund (@yonatman) May 21, 2020
–
Cross-immunity is the fact that by being infected with other coronaviruses, part of the population has generated antibodies which persist in their organism and which protect them against Covid-19. There are many forms of coronavirus, Covid-19 is one of them.
“A potential for pre-existing immunity”
A finding which does not allow drawing any conclusion, specify the authors of the study, who note however that there is “a certain potential for preexisting immunity in the human population”. Another study, published in the American journal Nature, shows that an antibody present in a patient infected with SARS in 2003, one of the most serious forms of coronavirus, shows good efficacy against Covid-19, reports Futura-sciences.
While it is unlikely that SARS patients in 2003 would be immune to Covid-19, study authors say, identifying the antibody could speed up the search for an effective treatment. What strengthen the hypothesis of cross immunity.
An explanation to several mysteries
A hypothesis that could explain certain mysteries around the Covid-19, such as the low mortality in many African countries.
An idea already advanced by Professor Omar Sarr, professor-researcher at the Faculty of Medicine of the University Cheikh Anta Diop of Dakar (UCAD): “There is a cross immunity due to a long exposure to various microorganisms and a good vaccination coverage, including BCG, a tuberculosis vaccine, “he explains to AFP.
This could also explain the low infection in children. “Being often exposed to colds, they may have developed immune reactions that continue to protect them for several coronaviruses,” says Youssef Oulhote, a professor researcher in epidemiology at the University of Massachusetts in the United States, who specifies that he does not it is only an “assumption”.
Collective immunization faster?
This “potential for pre-existing immunity” could therefore redefine the objective of collective immunization, ie the moment when a sufficient percentage of the population has developed antibodies so that the epidemic can no longer spread and end. by going out.
“This collective immunity can be obtained by natural infection or by vaccination,” recalls the Pasteur Institute, which estimates that, given the current state of scientific knowledge, about 70% of the population must be affected. . However, according to the latest estimates published in Science, approximately 4.4% of the French population is affected.
Depending on the proportion of the population enjoying cross-immunity, collective immunity may be achieved more quickly than expected. In the study published in Cell, 40 to 60% of healthy individuals are carriers of cells generating antibodies to Covid-19.
–
