COVID19 Antibodies Improve for Months After mRNA Vaccine

(Reuters) – Antibodies induced by mRNA COVID-19 vaccines keep improving in quality for at least six months while the immune system continues to “train” its antibody-producing B cells, according to a new study.

After vaccination, some B cells become short-lived antibody-producing cells, while others join germinal centers in lymph nodes – essentially, a training camp where they mature and perfect their skills.

“Cells that successfully graduate (from germinal centers) can become long-lived antibody-producing cells that live in our bone marrow or ‘memory B cells’ that are ready to engage if the person gets infected,” explained Ali Ellebedy of Washington University in St. Louis.

Animal studies have suggested that so-called germinal center reactions last only weeks. But analyses of blood, lymph node tissue and bone marrow from volunteers who received the Pfizer/BioNTech vaccine showed germinal center reactions induced by the shots lasted at least six months, with antibodies becoming increasingly better at recognizing and attacking the spike protein of the original version of SARS-CoV-2, Ellebedy’s team reported in Nature.

They did not test the mature antibodies’ ability to neutralize variants, but in theory, Ellebedy said, the antibodies should be better able to recognize parts of the spike common to the variants and the original strain.

More research is needed to know whether this robust germinal center response is unique to mRNA vaccines or if it is also induced by more traditional vaccines, he said.

SOURCE: https://go.nature.com/3I7LGPR Nature, online February 15, 2022.

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