Flu Infection at UPHS

Using samples collected from individuals after influenza virus vaccination, the investigators have shown that immune cells primed by previous influenza exposures are recruited to produce antibodies against newer viral strains. The investigators previous work indicate that the majority of the immune cells that respond to influenza vaccination are from the memory compartment, suggesting that 'immune imprinting' greatly affects the specificity of antibodies elicited by influenza vaccines. It remains less clear how prior influenza virus exposures impact immunity elicited by influenza virus infections. Compared to vaccinated individuals, it is more difficult to enroll influenza virus infected patients and track their immune responses over time. Viral antigens can persist for longer amounts of time following influenza virus infections relative to influenza vaccinations. It is therefore possible that influenza virus infections more efficiently prime de novo immune responses compared to influenza virus vaccinations. In this study, the investigators will longitudinally collect serum, PBMC, and respiratory samples from influenza virus-infected individuals from the University of Pennsylvania Health System characterize the cellular and humoral immune responses elicited by influenza virus infections.