Lifelong immunity of disease vs. short-term immunity of vaccine

The American Medical Association Family Medical Guide (Cover page, Publication information)

Chickenpox is a mild, though irritating, disease.  You can expect a complete recovery and consequent life-long immunity.

Chickenpox - Floyd Medical Center

Most people already know that it is unusual for someone to get chickenpox twice.

Chickenpox or Vaccine: A Choice? - Massachusetts Institute of Technology

First, a few words about chickenpox in children. Here's the best description I've seen: "Chickenpox is most commonly an annoying illness lasting three to seven days, and happily never seen again." Usually the worst part about it is that a parent has to lose a few days of work caring for the child. The best part--and it is a very good part--is that having chickenpox gives you lifelong immunity. Once you have had chickenpox, you will never get it again.