Vizzini's test in The Princess Bride reminds me of COVID

In The Princess Bride, the character Vizzini's had his wits tested when he had to choose to drink from one of two cups of wine, knowing that one of the two was poisoned.

**spoiler**

It's a trick. Both cups were poisoned and Vizzini's drinking competitor had previously built up an immunity to the poison.

Today, in real life 2021, people wonder, should they take the vax or rely on their own immune system? If they take the vax, which one?

Tricky stuff.