Answer
Through adaptive immunity, the snake handler's reaction to either the antivenin or the venom itself may change significantly after the first exposure as their immune system responds to the familiar foreign compounds.
Work Step by Step
After the first exposure to both the venom and the antivenin, the handler's immune system will have attempted to adapt to them.
Some antivenins do become less effective over time in the same patients due to this response, with some even becoming dangerous to administer too many times. Similarly, some venom becomes less effective after repeat bites or stings to the same person.
