Difference between DPT and DTaP vaccines?

What is the difference between the DTP vaccine and the DTaP vaccine? I heard something about one version being a dead form of a bacteria and thus less contagious and another version using a live bacteria and thus increasing the likelihood of contracting the illness.

Do you recommend asking for one version of the vaccine over the other?



Robert Steele

Robert W. Steele, MD, is a board certified pediatrician at St. John's Regional Health Center in Springfield, MO. He graduated from medical... Read more

The pertussis vaccine, the "P" part of the DTP which is the immunization against whooping cough, has had a lot of notoriety associated with it for many years. This is because it was the vaccine most associated with side effects. By far, the most common side effects were soreness at the injection site, fever, and irritability. These are not necessarily unusual side effects of vaccinations. However, the pertussis vaccine seemed to cause unusually high fever and extreme irritability in some children. Then, there came reports of significant brain injury called encephalitis being caused by the pertussis vaccine. Careful investigation by the Centers for Disease Control never convincingly associated this vaccine to this brain injury, but the reputation for this vaccine soon plummeted in the eyes of the public. There was relative wide-spread refusal by parents of any vaccine containing the pertussis portion. This was unfortunate because the infection rate of whooping cough came storming back with large outbreaks in several cities in 1993. However, refusal was understandable as well because of the concern by parents for their children.

The reason the pertussis vaccine had been so highly associated with fever and irritability is because of the components which make it up. The bug that causes whooping cough is a bacteria. And the vaccine was essentially made up of a killed version of this bacteria. In other words, the vaccine contained all the parts of the dead bacteria and was named the "whole-cell" vaccine. However, researchers soon realized that perhaps a better vaccine would be one that included those parts of the bacteria which allow for the body to become immune but leave out the parts that cause the fever and irritability. The fruits of this research became available a few years ago when the "acellular" vaccine was approved by the FDA. The word acellular describes the fact that this vaccine does not contain the "whole" bacteria cell but rather only the parts of the cell that allow for the body to develop good immunity. So, the name DTP was modified for this acellular vaccine and called the DTaP. The "a" stands for acellular.

New vaccines and new combinations of vaccines seem to be coming out almost monthly, so your confusion is completely understandable. Quite honestly, it is becoming increasingly difficult for pediatricians to keep up with all the changes. But without further delay, I will answer your questions.

Both vaccines contain only killed bacteria. Therefore, neither vaccine can actually give you the disease. So, any concern you might have about live versus dead bacteria in these vaccines is unwarranted. The regular or whole-cell DTP has all the parts of the bacteria in it while the DTaP has only a few parts. Studies have clearly shown the DTaP to have far fewer side effects including fever and irritability. In addition, several large well-done studies both in the U.S. and abroad have shown the DTaP to impart much better and longer lasting immunity in children. Therefore, I highly recommend you ask for the DTaP rather than the DTP.

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