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People who have survived COVID-19 may have some protection against reinfection after all, a new study suggests.
Scientists at Rockefeller University have found that one type of immunity, derived from memory B cells, lasts for at least six months.
B cells “remember” how to make antibodies against viruses, including the one that causes COVID-19.
And these cells are probably less easily fooled by mutations in the spike protein of “super-covid” variants like the more infectious British form, B117, compared to the antibodies themselves.
The variant has now been found in at least 17 US states, according to DailyMail.com tracking.
At least four more variants have emerged on American soil, and more from South Africa and Brazil could arrive and fuel a surge of cases overnight – especially now that the Trump administration has lifted it. his travel ban.
Scientists are concerned that mutations in the spike protein that allow the coronavirus to infect human cells may make the less “ visible ” variants of antibodies from previous episodes with COVID-19 or vaccines.
But B cells can help solve this problem, suggests new research published Monday in Nature.
Six months after developing COVID-19, 78 patients still had “ memory ” B cells for the coronavirus in their intestines (red, blue, and green on the slides). These B cells were also able to produce neutralizing antibodies in other lab tests.
This is because individual antibodies are quite specific to the virus they learned to fight first.
But B cells “evolved” after patients healed and “express antibodies with increased neutralizing potency and magnitude,” the researchers wrote.
When they tested specific antibodies against the HIV viruses they engineered to have peaks of mutant coronaviruses on their surfaces, the antibody responses were random, not always neutralizing the infectious peaks in the lab.
But the B cells lying around in the patients’ bodies, evolving for six months, not only recognized the coronavirus in disguise, but also produced antibodies capable of fighting it.
Specific “memory B cells” remain in the body and proliferate rapidly and generate antibodies against the virus.
Plus, they’re more potent than their original counterparts – and may be more resistant to mutations.
Past infection was linked to an 83% lower risk of contracting the virus compared to those who never had it.
“The activity of neutralizing antibodies decreases over time. But the number of memory B cells remains unchanged, ” corresponding study author Dr Michel Nussenzweig of Rockefeller University in New York said.
“In addition, they may be more resistant to mutations in the virus spike protein that mediates entry into cells.
This has important implications for the immunization program.
“Memory responses are responsible for protection against reinfection and are essential for effective vaccination,” said Dr Nussenzweig.
At least 105 ases of the British B117 ‘super-covid’ variant have been detected in 17 US states (red and pink) and at least three other variants have emerged
“ The observation that B cell memory responses do not break down after 6.2 months – but continue to evolve – strongly suggests that infected individuals could develop a rapid and effective response to the virus upon re-exposure . ”
The results are based on 87 Covid-19 patients aged 18 to 76 whose blood samples were analyzed twice – one month and just over six months after diagnosis.
Professor Michel Nussenzweig said: “These observations demonstrate that memory B cells have the ability to evolve in the presence of small amounts of persistent viral antigen – small proteins that can be detected by the immune system.
“The continued presence and evolution of memory B cells suggests that people may be able to rapidly produce potent neutralizing antibodies against viruses upon reinfection.
It follows a study by Public Health England last week that found immunity to last for at least five months.
The human immune system responds to infection by producing antibodies that can specifically neutralize the infectious agent.
Professor Nussenzweig said: “Immunity can last for at least six months. Levels of specific memory B cells remained constant over the study period.
“People who have already been infected can potentially organize a quick and effective response to re-exposure.
Human antibodies to Covid-19 have been shown to protect against infection in animal models
Professor Nussenzweig added: “The levels of these antibodies can decrease over time.
“But memory B cells – as the name suggests – ‘remember’ the infectious agent and can cause the immune system to produce the same antibodies upon reinfection.
It is increasingly evident that immunity lasts longer than previously feared. But experts have warned that people are catching Covid-19 again – and can infect others.
And officials stress that people should follow the rules of staying home whether or not they have contracted the virus.
Professor Susan Hopkins, of Public Health England, says it is of particular concern that some of those who were re-infected had high levels of the virus – even without symptoms.
She said: ‘This means that even if you think you already have the disease and are protected you can be reassured that you are very unlikely to develop serious infections, but there is still a risk of contracting it. infection and pass it on to others.
“Now more than ever, it is essential that we all stay at home to protect our health services and save lives.
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