Antibody Response to Flu Shaped by Pre-Existing Immunity December 14, 2020 Receiving the seasonal flu vaccine each year, in addition to seasonal infections, exposes people to a lifetime of building up immune responses to influenza antigens. Yet, it remains unclear whether infection and vaccination induce distinct influenza-specific immunological memory. A team led by researchers at the University of Chicago compared antibodies produced by individuals after influenza infection or vaccination. The authors found that a person’s antibody response to influenza viruses is dramatically shaped by their pre-existing immunity, and that the quality of this response differs in individuals who are vaccinated or naturally infected. Their results highlight the importance of receiving the annual flu vaccine to induce the most protective immune response.