You Do Need power plug adapter while traveling from Cameroon 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 Cameroon are C and E. This is how they look like.

Cameroon

In Cameroon, outlets of type C and E are in use.

Type C

Type E

Vatican City

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

Type C

Type F

Type L