MODEL RELEASED. Pre-school DPT booster. A 4-year- old boy receives a pre-school booster vaccination against diphtheria and tetanus by injection in the upper arm. The booster complements three courses of the triple DPT vaccine against diphtheria, pertussis (whooping cough) and tetanus, given to the child in his first year. Although the DPT vaccine does not provide absolute protection it greatly reduces the risk of serious illness. Diphtheria, pertussis and tetanus can all be fatal in an unimmunized child.