evidence: At a Glance - Researchers showed that B cells evolve after COVID-19 vaccination to help improve protection against SARS-CoV-2 over time. [...] Vaccines are the best way to protect yourself against COVID-19. They elicit a strong defense against SARS-CoV-2, the virus that causes the disease. Vaccines activate your body’s disease defense system, called the immune system. The response starts by engaging two kinds of immune cells: B cells, which produce antibodies that fight off the virus, and T cells, which destroy infected cells. [...] The B cells in the blood peaked one week after the second vaccine dose and then quickly disappeared. In contrast, the B cells in the lymph nodes persisted for six months, during which they significantly changed. The antibodies made by these cells became better at binding to and neutralizing the virus. The B cells in bone marrow samples taken six months after the second vaccine dose were similarly improved, suggesting that they were derived from the lymph node B cells.