Should my cat get the Feline Leukemia vaccine?

I have a 10 month old kitten who has not had the Feline Leukemia shot. When I took him in for his first vet visit they told me he wouldn’t need it unless he was going to be an outdoor cat or around other cats.

In May we are going on vacation and a friend offered to take Reggie for the week. She has two cats (both indoor) who have both had the vaccine. Does this mean I still have to get it for mine? Or does their having had the vaccine cover any chances that Reggie might get leukemia from them?