Dear Nix & Pat,
Here's the scoop. Whooping cough can be a deadly disease in infants. Adults and older children, especially those previously immunized against whooping cough don't get anywhere near as sick, even though they may cough for months. The current DTaP vaccine provides reasonable protection to infants, but can't be started before 6 weeks of age, and after only one dose certainly doesn't completely protect an infant.
The current and previous vaccines, as well as they worked, do not provide lifelong immunity against whooping cough. It is well known that older children and adults can be carriers of pertussis, the germ which causes whooping cough, and that they are the major source of exposure for infants. The problem is that there hasn't been a vaccine against whooping cough which was safe and approved for use in anyone 7 years old or older, until recently. Now there is a vaccine called Adacel (TdaP) which is approved for ages 11 years to 64 years old. As an additional means of protecting newborns and young infants against whooping cough, it is recommended that all those who have close contact with these infants (like parents and grandparents) receive a whooping cough booster by getting the TdaP.
The vaccine does not have anything live in it. It is doubtful that its use has been studied with people on medications since vaccines are intended to be given to people who are not acutely ill (but are often recommended for patients who are chronically ill). In any event, since ePocrates, the program I use for drugs, does not have a listing for BCG, I cannot do a check for interactions; however, all vaccines have been well studied for interaction with each other because we have so many vaccines we now have to give at the same time. They have all been shown to be safe given together and none to interfere with the immune respone to the other. Given that BCG works primarily as an immune system stimulant to help the body fight the cancer locally, given that their are no major byproducts of vaccines excreted in the urine, and given that being adequately immune to other illnesses and having a good working immune system does not interfere with the function of BCG, I cannot see any reason why a person receiving BCG couldn't receive the TdaP vaccine... but please understand that my opinion is an educated guess and not based on any studies of the matter.