Diphtheria is an infection caused by bacteria that releases toxins in the body. It can be life-threatening. The infection and toxins causes a thick coating in your nose and throat. This coating can make it hard to breath. Diphtheria can be easily spread between people.

Tetanus (also known as lockjaw) is caused by bacteria that enter through broken skin. The bacteria release a toxin in the body. It affects the nerves leading to severe muscle spasms. If it affects the muscles you need to breathe, it can be fatal.

Pertussis is also known as whooping cough. It is caused by bacteria that easily spread from person to person. It cause swelling in the airways. This causes a distinct, severe cough and breathing problems.

DTaP is a vaccine to protect against these three infections.

The vaccine has inactive forms of these bacteria. Inactive forms can not cause an infection. Instead, they stimulate the body to make antitoxins and antibodies to fight future infections.