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Another sign that there is light at the end of the tunnel in relation to the covid-19 pandemic. A new study suggests that immunity to COVID-19 could last for years and maybe even decades, thus giving hope that the vaccine could kill the new coronavirus, advances the New York Times.
According to the new data, most people who have recovered from the infection have enough immune cells to protect themselves from the virus and prevent disease eight months after infection, and it appears that these cells can persist in the body for much longer. .
The research, published online, has not been peer-reviewed or published in a scientific journal, but it is the most comprehensive study of immune memory related to coronavirus to date.
“This amount of memory is likely to prevent the vast majority of people from getting serious illnesses for many years.”said Shane Crotty, a virologist at the La Jolla Institute of Immunology in the United States, who led the new study.
The findings are likely to relieve experts concerned that immunity to the virus may be short-lived, which would mean that vaccines would have to be administered repeatedly to keep the pandemic under control.
This research focuses on another recent discovery: Survivors of SARS, caused by another coronavirus, still carry certain important immune cells 17 years after recovery.
Researchers at the University of Washington, led by immunologist Marion Pepper, have previously shown that certain “memory” cells that were produced after coronavirus infection persist in the body for at least three months. And a study published last week also found that people who recovered from Covid-19 have immune cells that are powerful and protective even when the antibodies are undetectable.
These studies “are all painting the same picture, that after a critical first few weeks, the immune response seems pretty conventional.”said Deepta Bhattacharya, an immunologist at the University of Arizona.
Akiko Iwasaki, an immunologist at Yale University, said she was not surprised that the body had a lasting response because “this is what should happen.” Still, she was excited about the investigation: “This is exciting news”.
A small number of infected people in the new study did not have lasting immunity after recovery, perhaps due to differences in the amounts of coronavirus they were exposed to. But vaccines can overcome this individual variabilitysaid Jennifer Gommerman, an immunologist at the University of Toronto. “This will help focus the response, so you don’t get the same kind of heterogeneity that you see in an infected population,” he said.
These new data contradicts concerns recently raised by reports that lowered antibody levels could cause immunity to disappear after a few months, leaving people vulnerable to reinfection.
However, many immunologists emphasize that it is natural for antibody levels to drop as they are only a small part of the immune system. And while they are necessary to block the virus and prevent a second infection, something known as sterilizing immunity, the immune cells that “remember” the virus most often are responsible for preventing serious illness.
“Sterilization of immunity does not happen very often, this is not the norm”said Alessandro Sette, an immunologist at the La Jolla Institute of Immunology.
What happens more often with reinfections is that the immune system recognizes the invader and quickly extinguishes the virus, especially since COVID-19 is particularly slow to cause damage, giving the immune system enough time to act.
For this study, Alessandro Sette and his colleagues recruited 185 men and women, ages 19 to 81, who recovered from COVID-19. Most had mild symptoms, which did not require hospitalization. And most of the people involved in the study provided only one blood sample, while 38 provided multiple samples over many months.
The team followed four components of the immune system: antibodies, B cells that make more antibodies as needed; and two types of T cells that kill other infected cells. The idea was to build a picture of the immune response over time, looking at its components. “If you look at just one, we could miss the whole picture,” Crotty said.
The study is the first to map the immune response to a virus in such detail, experts say.
