You Do Need power plug adapter while traveling from Vatican City to Hong Kong.

Here is Why You Need An Adapter

The outlet and plug type used in Hong Kong is G and in Vatican City are C, F and L. This is how they look like.

Vatican City

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

Type C

Type F

Type L

Hong Kong

In Hong Kong, outlets of type G are in use.

Type G