Influenza vaccine-induced human bone marrow plasma cells decline within a year after vaccination

A universal vaccine against influenza would ideally generate protective immune responses that are not only broadly reactive against multiple influenza strains, but also long-lasting. Because long-term serum antibody levels are maintained by bone marrow plasma cells (BMPC), we investigated the production and maintenance of these cells after influenza vaccination. We found increased numbers of influenza-specific BMPC four weeks after immunization with the seasonal inactivated influenza vaccine, but numbers returned to near their pre-vaccination levels after one year. This decline was driven by the loss of BMPC induced by the vaccine, while pre-existing BMPC were maintained. Our results suggest that most BMPC generated by influenza vaccination in adults are short-lived. Designing strategies to enhance their persistence will be a key challenge for the next generation of influenza vaccines.