The DTaP vaccine is a combination vaccine that protects against three serious diseases: diphtheria, tetanus, and pertussis (whooping cough). It is typically given to children in a series of five doses, starting at two months of age. The vaccine helps the immune system recognize and fight these infections, which can lead to severe health complications. Diphtheria is a bacterial infection that can cause breathing problems, while tetanus is caused by bacteria that enter the body through wounds and can lead to muscle stiffness. Pertussis is a highly contagious respiratory illness that can be particularly dangerous for infants. The DTaP vaccine is essential for preventing these diseases.