Covid: immunity longer and stronger in people infected

Published by Cécile D., Laurent P. · Updated on 14 June 2021 at 12h59 · Published on 13 June 2021 at 18h52
Several studies released in May 2021 confirm Covid-19 infection gives stronger immunity likely to last for several years. Injecting the vaccine could enable to strengthen the positive effects against the virus.

In August 2020, an American study released in preprint on Medrxiv, some “neutralizing” antibodies are particularly effective against a Covid-19 reinfection. It shares the experience sailors on a fishing boat in Seattle have lived and their health misfortune. According to scientists, three of the sailors on the boat had been already infected by the virus and developed antibodies able to face it, and had not been re-infected after being exposed to the virus again once on the sea.

The study embodied a lot of hope facing with a very little known and controlled disease. Asked about the results, molecular virology professor at the Nottingham university Jonathan Ball can only say: “it suggests that individuals who have had a prior exposure to virus are susceptible to reinfection unless they have appreciable levels of neutralizing antibodies”. He goes on: “this gives us an important insight into the type of immunity that might protect from future infection”.

This is a very significant finding” searcher at the  London School of Hygiene and Tropical Medicine John Edmunds explains. He adds: “It suggests neutralizing antibodies can protect against infection.” 

Almost a year following this discovery, scientists are more confident: several independent studies released in varied scientific magazines in May 2021 suggest immunity in people infected is stronger and could last between one and several years. A Covid-19 vaccine injection could even reinforce immunity making patients far more resistant against variants.

These studies confirm first that antibodies developed past the disease remain in the body for at least 13 months.

"We knew antibody levels never stay very high up in the blood, but since it is a respiratory virus and we usually do not track their serology over time, people did not dare going too far ahead on the matter. There, we eventually see antibodies remain stable in a persistan fashion and this is very good news" Head of Strasbourg virology institute Sammira Fafi-Kremer says as she led a study on the city university hospital health staff, released in preprint on May 15

Searchers from Ali H. Ellebedy's American team have discovered that antibodies developed by people infected are long-lasting plasmocytes. There are also found in bone marrow and keep on secreting antibodies against SARS-CoV-2 long months past the infection. "Long-lived bone marrow plasma cells (BMPCs) are a persistent and essential source of protective antibodies", the study read.

American searchers add yet the fact not everyone can develop equal immune defense. Patients must stay cautious. Fortunately, Covid-19 vaccines enable to reinforce barriers against the virus in an effective way.

"Clearly, the best configuration is people who have had mild Covid-19 followed by a vaccine injection: these are champions of immune response against SARS-CoV-2" head of immunology center and infectious diseases at Paris La Pitié-Salpêtrière hospital Guy Gorochov explains. "It is clear vaccination boosts antibodies and memory, so we can hope and be protected for several years", Fafi-Kremer confirms.

The scientific confirms "immunity in people simply vaccinated will probably not be as strong as in people already infected because infection generates antibodies against several proteins of the virus".

This affirmation - shared by her peers - urges experts to claim for a third dose of vaccine likely to help one's body build immunity enabling to fight against the most aggressive variants and extend antibodies' lifespan.

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