Potential Impact of Changes in the Schedule for Primary Diphtheria-Tetanus Toxoids-Pertussis Immunization as Control Strategy for Pertussis.

Background: Pertussis is a vaccine-preventable respiratory disease that may cause death mainly in infants. The schedules for primary pertussis vaccination are set in each country by the local health authorities. Several different schedules meet World Health Organization recommendations, 2-4-6 months, 6-10-14 weeks, 2-3-4 months and 3-4-5 months being the most commonly used worldwide.