Impact of Bacterial Expression and Immune Response in the Severity of Pertussis

Inclusion Criteria: * be between the ages of 0 and 15 years inclusive * be suspected of having pertussis by the physician in charge, with the prescription of a diagnostic PCR (pertussis PCR, which may be a syndromic PCR, a PCR targeting IS481 and/or IS1001) * be free of any pathology/treatment that may influence the immune response (autoimmune/inflammatory pathology or immune deficiency not listed above, hepatic insufficiency, taking immunosuppressive treatment (including taking oral corticosteroids with a dose ≥ 10 mg/d Prednisone equivalent for more than 15 days) * Have received age-appropriate information and written assent or consent from their parents/legal guardians * be affiliated with or benefiting from a social security plan Exclusion Criteria: * Patient with any pathology/treatment that may influence the immune response (autoimmune/inflammatory pathology or immune deficiency not listed above, hepatic failure, taking immunosuppressive therapy (including oral corticosteroids with dose ≥ 10 mg/d prednisone equivalent for more than 15 days) * Use of antibiotics active against pertussis in the 24 hours preceding the sampling * Delay between the result of the diagnostic sample (pertussis PCR) and the day of inclusion \> 48 hours * Patient's condition that, in the opinion of the physician, is incompatible with the expanded/additional sampling(s) required by the study * Infant with a weight \< 2.5 kg at the time of inclusion.