Two months ago (at the start of Flu season) you decide to get a flu vaccine shot from your doctor. Your roommate decides not to get the flu vaccine this year because she got one last year. Two weeks ago you were both exposed to the flu - now you feel great and your roommate is laid up in bed sick with the flu. Based on your knowledge of vaccinations and viral antigenic variation, explain why your roommate's increased susceptibility to the flu? Why did her shot from last year not work and your shot from this year did work? Be detailed in your response and describe how influenza virus must have interacted with each of you based on the information provided in the scenario.