"With the absence of a flu vaccination last year, I did not take a flu shot; but there is still some immunity that carries over from year to year; but about every 30 years, there is a major change in the genetics of the flu virus"

This quote by Michael Burgess recommends that even without getting a flu vaccination in 2015, there is still some immunity that rollovers from year to year. However, he likewise keeps in mind that every 30 years, there is a major change in the genetics of the influenza virus. This implies that the resistance that rollovers from year to year may not be enough to protect against the brand-new stress of the virus. For that reason, it is necessary to get a flu shot every year to guarantee that you are secured against the most recent stress of the virus.