Local B cell immunity and durable memory after live-attenuated influenza intranasal vaccination of humans

) cells. Recently activated upper airway memory B cells were not readily detected in intramuscular vaccinees, despite the elevation of systemic antibodies and circulating HA-specific memory B cells. Thus, despite minimal immune responses detected in circulation, adults vaccinated with the live-attenuated influenza vaccine generate substantial local antigen-specific memory B cell responses. These findings have implications for improving influenza vaccines and for mucosal vaccination against other respiratory pathogens.