People who survived COVID-19 may have some protection against reinfection, after all, suggests a new study.
Scientists at Rockefeller University found that a type of immunity, from memory B cells, lasts at least six months.
B cells ‘remember’ how to make antibodies to viruses, including the one that causes COVID-19.
And those cells are probably less easily tricked by mutations in the peak protein of “supercovid” variants as the UK’s most infectious form, B117, compared to the antibodies themselves.
The variant has already been found in at least 17 U.S. states, according to the DailyMail.com tracking.
At least four other variants have emerged on American soil, and others from South Africa and Brazil could arrive and feed a wave of cases any day – especially now that the Trump administration has lifted its travel ban.
Scientists are concerned that mutations in the spike protein that allow the coronavirus to infect human cells may make the variants less ‘visible’ to antibodies from previous attacks with COVID-19 or vaccines.
But B cells can help solve that problem, suggests new research published in the journal Nature.
Six months after developing COVID-19, 78 patients still had coronavirus “memory” B cells in their intestines (red, blue and green on the slides). These B cells were also able to produce neutralizing antibodies in other laboratory tests
This is because individual antibodies are very specific to the virus they have learned to fight.
But B cells “evolved” after patients’ recovery and “express antibodies with greater potency and range of neutralization,” the researchers wrote.
When they tested specific antibodies to the HIV virus that they designed to have mutant coronavirus spikes on their surfaces, the antibody responses were right and wrong, not always neutralizing infectious peaks in the laboratory.
But the B cells that were hanging on patients’ bodies, evolving for six months, not only recognized the disguised coronavirus, but produced antibodies that could fight it.
Specific ‘memory B cells’ remain in the body and quickly proliferate and generate antibodies against the virus.
What’s more, they are more powerful than their original counterparts – and may be more resistant to mutations.
Previous infection was associated with an 83% lower risk of contracting the virus compared to those who never had it.
Neutralizing antibody activity decreases over time. But the number of memory B cells remains unchanged, ‘said the study’s corresponding author, Dr. Michel Nussenzweig, of Rockefeller University in New York,
“In addition, they may be more resistant to mutations in the virus’s spike protein that mediates entry into cells.”
This has important implications for the vaccine program.
“Memory responses are responsible for protecting against reinfection and are essential for effective vaccination,” said Dr. Nussenzweig.
At least 105 aces of the UK “supercovered” variant B117 have been detected in 17 US states (red and pink) and at least three other variants have emerged
‘The observation that memory B cell responses do not decline after 6.2 months – but instead continue to evolve – is strongly suggestive that infected individuals may respond quickly and effectively to the virus after reexposure . ‘
The results are based on 87 Covid-19 patients between the ages of 18 and 76, whose blood samples were analyzed twice – per 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 virus neutralizing antibodies after reinfection.”
He follows a study by Public Health England last week, which found that immunity lasted 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 at least six months. The levels of specific memory B cells remained constant during the study period.
‘Individuals who have been previously infected can potentially mount a quick and effective response after reexposure.’
Human antibodies against 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 -‘ resemble ‘the infectious agent and can cause the immune system to produce the same antibodies after reinfection.’
Evidence is growing that immunity lasts longer than previously feared. But experts have warned that people get Covid-19 again – and they can infect others.
And the authorities emphasize that people must follow the rules to stay at home – whether or not they have contracted the virus.
Professor Susan Hopkins of Public Health England says it is particularly worrying that some of those reinfected have high levels of the virus – even without symptoms.
She said: ‘This means that even if you believe you have had the disease and are protected, you can be sure that it is highly unlikely that you will develop serious infections, but there is still a risk of getting an infection and passing it on to others.
“Now, more than ever, it is vital that we all stay home to protect our health care and save lives.”