The DTaP vaccine protects your child against three serious bacterial infections: diphtheria, tetanus (lockjaw), and pertussis (whooping cough).
Diphtheria is an infection that causes the throat to swell, which can make it hard for children to breathe and swallow. If left untreated, toxins from the bacteria can also damage other organs, leading to paralysis and heart failure. While diphtheria used to be a common cause of death in children in the 1920s, decades of vaccination has made the disease virtually nonexistent in the U.S., though diphtheria outbreaks do still occur overseas.
Tetanus, also known as lockjaw, causes painful muscle spasms that can affect breathing and even cause heart damage. Unlike many other infectious diseases -- which children catch from other kids or adults -- tetanus bacteria live in the soil and are transmitted when a contaminated object (like a rusty nail) cuts the skin. A tetanus infection leads to death in up to 20 percent of cases.
Pertussis, also known as whooping cough, is a highly contagious infection of the lungs that can cause coughing spells (some so severe that children have trouble eating and breathing), and may lead to pneumonia and seizures. Infants under 6 months of age are most at risk. Before the vaccine, whooping cough caused about 9,000 deaths in the U.S. each year; now only about 10 children die from pertussis annually. Most children who get whooping cough are actually infected by adults, not other kids. Thousands of adolescents and adults still get whooping cough every year (immunity wears off over time if adults don't get the necessary booster shots).