Can an adult who has had all their vaccinations still get whooping cough? Is this possible, not possible or highly unlikely?

Depends on variables. Today's adults who had their shots as kids are rarely protected against whooping cough. This protection weakens in time & allows adults to get the disease and pass it to younger vulnerable infants.Before ~ 1994 whooping cough shots weren't given > age 6 due to major side effects, today we give tdap, a new vacccine with minimal side effects to adults to protect both them and the kids they visit.