8
votes
2answers
2k views

Why do I need a flu shot every year, while many other vaccinations last years or even a lifetime?

Is it a viral vs. bacterial thing? Is there just more variety among types of flu than other diseases, so that this year's vaccines don't cover next year's flu?
2
votes
2answers
66 views

Are B Cells unique to an individual's immune system?

I was wondering how the body "remembers" viruses after having once overcome them, and while reading this article on the immune system (page 14, Vaccinations), I read: There are many diseases that, ...