B Cell and Antibody Response to Seasonal Influenza Vaccines in Younger and Older Adults

This study is particularly focused on studying antibodies, a protein in blood that react with foreign substances (such as bacteria and viruses) to help eliminate them. This study will examine antibodies and the cells that they are produced by, B cells that develop in response to the influenza vaccine. The majority of antibodies that develop following seasonal influenza vaccine are highly specific for particular influenza strain that comprises the influenza vaccine, necessitating the annual reformulation of the influenza vaccine to match strains expected to be in circulation for the upcoming season. This is problematic, and strategies to develop an influenza vaccine that can promote the robust and persistent development of antibodies that are effective against a wide range of influenza strains are needed. One potential strategy is to promote antibody responses targeting the neuraminidase (NA) protein of influenza. NA is more highly conserved across influenza viruses as compared to the hemagglutinin (HA) protein which is the major component of the influenza vaccine. Thus understanding how differences in seasonal influenza vaccines may influence the quality and breadth of HA and NA specific antibodies is of importance in the development of more effective influenza vaccines. There are several FDA-approved seasonal inactivated influenza vaccines (IIVs) and it remains unknown the extent to which they may induce HA and NA-specific B cells and antibodies, and particularly those that may have broad protective activity against influenza. Differences in the various seasonal IIVs, such as how they were produced, their dose, and the immune stimulating components (adjuvant) they contain may influence the HA and NA-specific response. The two major types of seasonal IIV approved for adults are IIV that is comprised of inactivated influenza virus that was grown in chicken eggs (e.g. Sanofi Fluzone, IIV), and the other comprised of inactivated influenza virus that was grown in cell culture (e.g. Seqirus Flucelvax, cc-IIV). Additionally, for adults 65 years and older, High Dose Fluzone (HD-IIV3), and Sequris Fluad IIV, which includes an adjuvant (a-IIV3). This study will evaluate the relative induction of HA and NA-specific antibodies and B cells from adults immunized with these various seasonal influenza vaccines, and how these responses may change after each year, and differ in older adults who may have a different past exposure history to influenza compared to younger adults. The seasonal influenza vaccines will be given as standard of care, in populations they are approved for, and administered in approved dose and route.