New study found how effective modern coronavirus vaccine is still six months later

A study published by the United States National Institutes of Health (NIH, for its acronym in English) has ensured that the Moderna vaccine versus Covid-19 generates long-lasting immune memory, even in those who have been immunized with a quarter of the standard dose allowed by the FDA. The researchers had analyzed the antibody and T cell levels after the first and second doses, and after six months of completing the regimen.

According to the document published by the North American entity, this vaccine of Messenger RNA, near Pfizer, highlighted a efficiency greater than 90% after the second dose. However, although this response was thought to decrease sharply, scientists found the drop at six months to be slight, while cellular memory against the virus remains strong.

The scientists explained that in order to stop the infection, the response of the neutralizing antibodies is as important as the T cells, which are responsible not only for killing the pathogen, but also for remembering what it looked like and how to kill it, a key step if you want to know what is the protection left by vaccines against the coronavirus.

Led by Daniela Weiskopf, Shane Crotty and Alessandro Sette of the La Jolla Institute of Immunology, the researchers evaluated the immunological memory of approximately 35 volunteers who had participated in Phase 1 of the Moderna vaccine and that in addition, they had been immunized with a quarter of the standard dose authorized by the FDA (25 micrograms).

After analyzing antibody and T cell levels after the first and second doses, and six months after completing the regimen, they remained strong throughout this period. In addition, as they pointed out, the study analyzed two subsets of T cells: CD8 T cells (“killer” cells of the virus) and CD4 T cells (“helper” in the generation of antibodies. ) and in both cases the response remained strong six months after receiving the second dose, and was even comparable to those expressed by the recovered individuals.

“The immunological memory remained stable, and it was impressive,” Shane Crotty told the North American panel and added, “It is a good indicator of the durability of mRNA vaccines.” It should be noted that this research was funded by the National Institute of Allergy and Infectious Diseases (NIAID) of the NIH.