You Do Need power plug adapter while traveling from Pitcairn Islands to Vatican City.

Here is Why You Need An Adapter

The outlet and plug type used in Vatican City are C, F and L and in Pitcairn Islands is I. This is how they look like.

Pitcairn Islands

In Pitcairn Islands, outlets of type I are in use.

Type I

Vatican City

In Vatican City, outlets of type C, F and L are in use.

Type C

Type F

Type L