Poly-omic Predictors of Symptom Duration and Recovery for Adolescent Concussion

Inclusion Criteria: * Presence of mTBI: defined by criteria from the Berlin Consensus Statement and WHO. Assessment for mTBI status be performed by a licensed clinician per the 2018 CDC guidelines. * Age at enrollment: 13-18 years of age (inclusive). Exclusion Criteria: * \> 48 hours after initial mTBI * Glasgow Coma Scale score of 13 or less * Previous moderate-to-severe TBI requiring overnight hospitalization * Unresolved symptoms from previous concussion, or any concussion within the last 3 months * Abbreviated Injury Scale (AIS) score \> 3 (to reduce confounding from poly-trauma) * Psychiatric illness requiring previous hospitalization; * Neurological condition (e.g. epilepsy, hydrocephalus) or abnormality on neuroimaging (if performed) * Intellectual disability that prevents ability to provide informed assent * Pregnancy * Active substance use/dependence * Previous neurosurgery * Non-fluency in English * Upper respiratory infection * Periodontal infection * Injury to the oropharynx * Previously enrolled in the same study * Inability to complete follow-up assessments