 The study found that repeat vaccination with split, inactivated flusonetamine for consecutive influenza seasons from 2013 to 2016 had varying effects on the breadth and durability of functional antibodies in individuals aged 18 to 85 years. Lunger subjects typically maintained high seroprotective titers, while elderly subjects HAI titers were generally lower and more likely to decline prior to the start of the next influenza season. Immunological recall or back boosting to antigenically related viruses was associated with seroconversion. The study demonstrated that age and influenza exposure history impact an individual's ability to respond to future influenza infections, eliciting broadly reactive immune responses within a lineage as well as cross-reactive immune responses between lineages. This article was authored by Michael A. Carlock, John G. Ingham, Emily F. Clutter, and others.