Observational Study Describing the Immune Profile Induced By Pertussis Vaccines

Inclusion Criteria: An individual must fulfill all of the following criteria in order to be eligible for study enrollment: Toddler Cohort: * Aged 15 to 24 months on the day of (V01) * Has received 3 doses of a licensed pertussis-containing vaccine for a priming series during infancy in accordance with the recommendations of the NIP or his / her primary care physician * Has written documentation (e.g., immunization record, physician's certificate, vaccination unit registry) available to verify the receipt of 3 doses of a licensed pertussis-containing infant vaccines as per national immunization schedule * ICF has been signed and dated by the subject's parent(s) / legally acceptable representative(s) and, if required, an independent witness, in accordance with local regulations * Planned receipt of routine pertussis booster vaccine, preferably, on same date as, and no more than 2 days following, V01 * Participant and parent / legally acceptable representative are able to attend all scheduled visits and to comply with all study procedures Preschooler Cohort: * Aged 48 to 59 months on the date of V01 * Has received 4 doses of pertussis-containing combination vaccines as per national immunization schedule Exclusion Criteria: An individual fulfilling any of the following criteria is to be excluded from study enrollment: * Participation at the time of study enrollment or planned participation during the present study period in another clinical study investigating a vaccine, drug, medical device, or medical procedure * Receipt of any vaccine in the 4 weeks preceding the study or planned receipt of any vaccine (other than a booster pertussis vaccine) between V01 and V03a * Receipt of immunoglobulins, blood, or blood-derived products in the past 3 months * Known or suspected congenital or acquired immunodeficiency, or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding 6 months, or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks) within the preceding 3 months * History of clinically- or laboratory-confirmed pertussis as per the WHO recommended case definition * Bleeding disorder, verbal report of thrombocytopenia, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating venipuncture, in the opinion of the investigator * Chronic illness that, in the opinion of the Investigator, is at a stage where it might interfere with study conduct or completion * Moderate or severe acute illness/infection (in the opinion of the investigator) or febrile illness (temperature ≥ 38.0°C) at physical examination on V01 of the study. A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided. * Receipt of oral or injected antibiotics therapy within the 72 hours preceding the first blood draw. (Topical antibiotics and antibiotic drops are not included in this exclusion criterion). * Identified as a natural or adopted child of the Investigator or an employee with direct involvement in the proposed study