A little less then a year ago i got my dog shots rabies, corona, 6in1 dhpp4l, and bordetella.?

what if i didnt get booster shots for the bordetella and im boarding my dog this thrusday. i just found out by my vet that he never got booster shots. he said it wouldnt affect the kennel cough. since he got the injection anyways a booster is just a system backup ncase the orignal vaccine fails. is this true?