People infected with the SARS-Cov-2 virus can be protected by their immune memory for at least eight months. But protection would not be conferred by antibodies, which have been shown to decline over time, but by memory B cells, says research carried out in the Monash University, Alfred Hospital and Burnet Institute (Australia) and published in « Science Immunology».
Research is the strongest evidence solid which shows that coronavirus vaccines can be effective for long periods.
The key would be in these specific cells of the immune system, called memory B cells, which are capable of «remember»Infection with the virus and, if it recurs, elicits a protective immune response by rapidly producing antibodies.
Their data comes from a group of 25 Covid-19 patients, from whom they obtained 36 blood samples from the fourth day after infection to day 242.
As with other studies, looking at just the antibody response, the researchers found that antibodies began to decline within 20 days of infection.
However, all patients continued to have memory B cells that recognized one of the two components of the SARS-CoV-2 virus, the nucleocapsid and spike proteins.
«All samples contained IgG antibodies to SARS-CoV-2, but samples obtained at 20 days or later showed a marked decrease in antibody levels.. In contrast, memory B cell levels continued to increase in samples obtained before 150 days, and this trend was also correlated with circulating follicular helper T cell levels, suggesting that the immune system of patients was prepared to respond to reinfection, “they write.
These virus-specific memory B cells were stably present for up to eight months after infection.
According to the coordinator of the work, Menno van Zelm, the results provide esperanza about the effectiveness of any vaccine against the virus and also explain why there have been so few cases of reinfection among the millions of people who have tested positive for the virus around the world.
“These results are important because they definitely show that patients infected by the coronavirus retain their immunity against the virus,” they conclude.