Quote Originally Posted by CoccoBill View Post
Most vaccinations require boosters. Flu shots (against coronaviruses) are taken annually, same with almost all childhood vaccinations.
I think the influenza virus is a different type of virus than coronaviruses (which are generally associated with colds, not 'flus), and the reason 'flu shots are yearly is because there is a different strain that predominates each year, and the vaccine gets customised to that strain.

There are certain vaxxes that are good for life because the immune system has a better memory for certain antibodies than for others. Coronaviruses are a type of virus the immune system has a poor memory for, and this is why we benefit from having frequent boosters. It's also why you never become fully immune to colds the way you do to, say, chicken pox or mumps; even after multiple infections your immune system does not remember colds. But chicken pox or mumps it remembers for life, so you get them once and that's it.