The vaccine doesn't work 100%. I got the shot about 3 years ago.
I asked the doctor then if I should need a boost. She said, because
it's still in the early stage, they don't know how long it'll last.
So, about 3 months ago, I went to my university's hospital and checked
whether I need another boost. The only way they know if I need a boost
is by drawing my blood. The darn nurse missed my vein 4 times, until she
gave up and called another nurse. He made a hole out of me just to draw the blood.
Anyway, my blood work came out negative, as if I never got the shot.
So, I had to get 2 more vaccine shot. I hope this time I am immune to chicken pox.
Just to let you know, they injected live virus, so there is a chance
you'll get the chicken pox from the vaccine although a small ome.
If you are not 100% healthy the chance of you getting it becomes even higher.