text: Vaccination boosts protective responses and counters SARS CoV 2 induced pathogenic memory B cells Much is to be learned about the interface between immune responses to SARS CoV 2 infection and vaccination We monitored immune responses specific to SARS CoV 2 Spike Receptor Binding Domain RBD in convalescent individuals for eight months after infection diagnosis and following vaccination Over time neutralizing antibody responses which are predominantly RBD specific generally decreased while RBD specific memory B cells persisted RBD specific antibody and B cell responses to vaccination were more vigorous than those elicited by infection in the same subjects or by vaccination in infection naïve comparators Notably the frequencies of double negative B memory cells which are dysfunctional and potentially pathogenic increased in the convalescent subjects over time Unexpectedly this effect was reversed by vaccination Our work identifies a novel aspect of immune dysfunction in mild moderate COVID 19 supports the practice of offering SARS CoV 2 vaccination regardless of infection history and provides a potential mechanistic explanation for the vaccination induced reduction of Long COVID symptoms 