A 2-month-old male is brought to the emergency department via ambulance for evaluation of apnea. The mother states that he was previously well until a few days ago when he developed mild rhinorrhea and nasal congestion. He had no further symptoms until the day of presentation when he stopped breathing for 20–30 seconds and turned blue. EMS was called and brought him in for evaluation. He was born full term, via normal spontaneous vaginal delivery, with no complications. He was discharged home with the mother after 24 hours and has been healthy up until this illness. He lives at home with his parents, a 9-year-old brother and a 15-year-old sister. The mother states that she has had colds and allergies presenting as cough over the past few weeks. There have been no other exposures or sick contacts. The infant does not go to daycare. Due to persistent and worsening apnea, bradycardia, and desaturations in the emergency department, the patient is intubated and placed on mechanical ventilation. A complete blood count (CBC) shows a total leukocyte count of 44,000 cells/μL, with 90% lymphocytes and 10% neutrophils. The remainder of the CBC, electrolytes, and hepatic function panel are within normal limits. A chest radiograph is benign. Blood cultures are negative. A posterior nasopharyngeal swab is positive for Bordetella pertussis by polymerase chain reaction (PCR). A 5-day course of azithromycin is initiated. On further questioning, the 9-year-old brother last received a pertussis-containing vaccine at 4 years of age. The 15-year-old sister received her last pertussis-containing vaccine at 11 years of age. The mother had not received a pertussis-containing vaccine booster since childhood since she had declined the recommended Tdap vaccine during her third trimester of this pregnancy. Chemoprophylaxis with azithromycin is provided to all of the household contacts and to the attending physician who performed the intubation.