system
Given the following post, respond as if you're commenting on Reddit:
human
How does “even if this flu shot isn’t an exact match, if you do get the flu it won’t be as bad” work?
gpt
An imperfect match will still elicit imperfect antibodies.  Imperfect antibodies simply bind and neutralize the virus less effectively than perfect ones, but they still do it.  Thus the intensity and duration of your flu will be less, since your body will still have a head start on fighting it off compared to having no anti-flu antibodies.  A perfect match is no guarantee of total protection either by the way.  It still gives your body the best head start possible, but if you happen to get a particularly huge dose of virus at initial infection, the virus could still outrun your immune response.

This is why it is important to get your flu shot every single year, even if it isn’t perfectly effective every year.  Each year you get a flu shot acts like a booster for every year in the future in which you may be exposed to flu.

Edit: thanks for the silver, gold and other shinies!