Tdap is the tetanus, diphtheria and pertussis vaccination. One Tdap vaccine is given at the age of 11 or 12; pregnant women should get an additional dose during every pregnancy, according to the Centers for Disease Control (CDC).
According to the CDC, tetanus causes painful muscle tightening all over the body. Diphtheria causes breathing problems and paralysis. Pertussis (whooping cough) causes severe coughing spells, with hospitalization in up to 5 percent of cases. All three diseases are bacterial in nature. Since the Tdap vaccine became routinely used, cases of tetanus and diphtheria have dropped by about 99%, and cases of pertussis have dropped by about 80%.