Conclusion
In this prospective cohort study of critical pertussis, elevated WBC and pulmonary hypertension were both associated with increased mortality risk. Most critical pertussis occurs in children too young to benefit from direct immunization. Studies to further characterize the course and immune biology of critical pertussis illness are needed to identify the risks and benefits of leukoreduction strategies, as well as other potential life-saving therapies. Furthermore, given that the vast majority of the world's children live in circumstances where advanced pediatric critical care services are unavailable, insight gained from contemporary pediatric critical care in the United States must provide readily assessed hematologic and hemodynamic data that can enhance our understanding of why B. pertussis still kills between 200,000 and 300,000 children annually, the vast majority developing world.