Scientists said on Monday that vaccines made by Pfizer-Biontech and Moderna companies have caused a continuous immune response in the body that may protect against the Corona virus for years.
The findings, published in the journal Nature, add to mounting evidence that most people who have been immunized with mRNA-based vaccines may not need booster doses for years, as long as the virus and its variants do not evolve much beyond their current forms, according to the newspaper. The New York Times.
In turn, the Egyptian researcher and immunologist at Washington University in St. Louis, Ali Al-Labidi, who led the study, said: “It is a good sign of the sustainability of our immunity from this vaccine.”
The study did not take into account a Johnson & Johnson coronavirus vaccine, but Al-Labadi said he expects the immune response to be less durable than that produced by mRNA vaccines.
Al-Labadi and his colleagues reported last month that in people who have survived COVID-19, immune cells that recognize the virus reside in the bone marrow for at least 8 months after infection. A study by another team indicated that so-called memory B cells continue to mature and strengthen for at least a year after infection.
Based on these findings, the researchers speculated that immunity could last for years, and possibly a lifetime, in people who have been infected with the coronavirus and subsequently vaccinated. But it was not clear whether vaccination alone might have a similarly long-term effect.
The team that prepared the study sought to address this question by looking at the source of memory cells, the lymph nodes, where immune cells are trained to recognize and fight the virus.
The study showed positive results, as after infection or vaccination, a specialized structure called the germinal center is formed in the lymph nodes. This structure is like a boot camp for B cells, as they become more complex and learn to recognize a variety of viral genetic sequences.
The difference is that after infection with the Corona virus, the germ center is formed in the lungs. But after the vaccination, the cells are cultured in the lymph nodes in the armpit.
Al-Labadi’s team found that 15 weeks after the first dose of the vaccine, the germinal center was still highly active in all 14 participants, and that the number of memory cells that recognized the coronavirus did not decrease.
Al-Lubaidi said, “The fact that the reactions lasted for about 4 months after the vaccination…is a very, very good sign.” The germinal centers usually peak one to two weeks after vaccination, and then fade away.
The results indicate that the vast majority of people who have been vaccinated will be protected in the long-term, at least, against the current variants of the coronavirus. But the elderly, people with weakened immune systems and those taking immunosuppressive drugs may need boosters, while people who have survived COVID-19 and were subsequently vaccinated will not need them at all.
It is difficult to predict exactly how long protection from mRNA vaccines will take. Experts said that in the absence of variants that avoid immunity, it is theoretically possible for immunity to last a lifetime.
The study also showed that people who were infected with the Coronavirus and then vaccinated had a significant increase in antibody levels, likely because their B cells – which produce antibodies – had several months to develop before vaccination.
The good news is that it’s possible that the booster vaccine will have the same effect as previous infections in immunized people, Labidi said.