The DPT or DTAP is an immunization or vaccine to protect against the diseases diphtheria, pertussis, and tetanus. Five doses are commonly given to children between the ages of two months to five years old. They provide lifelong immunity, in most cases to diphtheria and pertussis, but do not provide lifelong immunity to tetanus. Tetanus vaccinations need to be repeated every 8-10 years in order to remain effective.

One of the earliest vaccinations a baby receives is the DPT, since especially whooping cough or pertussis, and diphtheria are associated with high death rates and complications in young children. Tetanus is usually less common and most often occurs if people are exposed to dirt containing tetanus germs. This can happen if you get cuts on rusty fences, get dirt with tetanus germs into a cut, or you work around horses, where tetanus would be common if not for similar animal vaccinations.

Most children have mild reactions to the DPT vaccine. These include fever and crankiness for a few days after receiving the DPT vaccine, and soreness at the shot site, which is usually the thigh in infants and the arms in older children. 1% of children who receive the DPT vaccine may suffer moderate reactions, including crying that can last three hours or more, and fever of up to 105 F (40 C).

Very severe reactions to the DPT vaccine are extremely rare, occurring in about one in every 140,000 children. Children who are allergic to the shot components may go into anaphylactic shock right after receiving a shot. This is normally quickly addressed in a doctor’s office by giving the child an epi-pen or epinephrine injection. Children who have had an allergic reaction to the DPT vaccine do not receive future injections of the vaccine. This makes them more vulnerable to contracting these diseases, albeit a risk lessened when other parents immunize their children.

The most severe reactions are seizures, unconsciousness and death. Yet these risk factors are weighed against the much greater risk of dying from an illness against which the DPT vaccine protects. Studies in the 1990s suggested that the most common reactions are to the pertussis portion of the DPT vaccine. In the 2000s, the US began giving the DTAP, containing acellular, not whole cell, forms of pertussis. This is considered safer and just as effective in providing immunity against whooping cough.

Some differences in the preparation of the DPT vaccine exist between American and European forms. Concerns exist in the US that the preservatives in the vaccinations may pose additional risks to children. Europe does not use preservatives in their DTAP preparation. In particular, parents have been concerned about preservatives that contain mercury. It should be noted that the US no longer uses mercury-based preservatives in DPT vaccines.