Pertussis is a bacterial respiratory illness characterized by severe spasms of coughing that can last for several weeks or even for months. According to the CDC, in the United States, 5,000-7,000 cases of pertussis are reported each year. There has been an overall increase in cases since 1990, with a disproportionate increase in adolescents and adults. Pertussis is highly contagious, with up to 90% of susceptible household contacts developing clinical disease following exposure to an index case. Adolescents and adults who have been vaccinated as children often have mild or no symptoms, but may have classic pertussis. Infected individuals can pass the disease to non-immunized or not completely immunized infants, and the disease can be severe in these individuals. Due to the increased prevalence of pertussis, recent guidelines have recommended that tetanus boosters, which previously included diphtheria, should include pertussis as well. This combined vaccine (Tdap) should be given to adolescents. The Tdap vaccine can be given regardless of interval since the last tetanus or diphtheria-toxoid containing vaccine.