Adaptive Platform Trial of Treatments for Respiratory Infections in Community Settings (TreatResp)

Inclusion Criteria: * 18 years or older * A positive test (PCR or RAT) for one of the pathogens included in the trial's domains (influenza A/B, or other future specified respiratory pathogens), * Enrolled within 5 days of symptoms onset. However, this window may vary depending on the domain or specific interventions within each domain (for example 72 hours for Baloxavir). * At least two symptoms commonly associated with respiratory infections, including: * rhinitis * cough * wheezing * sore throat * nasal congestion * shortness of breath * fatigue * rapid breathing * excessive mucus production * loss of smell or taste * hemoptysis * trouble sleeping or insomnia due to breathing difficulties * fever (defined for purposes of this study as \>37.5°C/ 41). Exclusion Criteria: * Admitted to hospital or in an ED for more than 24 hours * Previously randomized to TreatResp within the past 12 months * Currently participating in a clinical trial of a therapeutic agent for acute respiratory pathogen infection that is not/suspected not compatible with the study therapeutics * Already taking a study therapeutic or contraindication to a study therapeutic * Inability for participant or caregiver to provide informed consent. Additional eligibility criteria will be applied based on the intervention assigned. For instance, if a participant is randomized to an antiviral treatment, they must not have contraindications specific to that antiviral. This ensures that each treatment is evaluated in a population for whom it is most appropriate and safe. Baloxavir exclusion: * Has a known or suspected pregnancy * Is breastfeeding * Is of childbearing potential and is not willing to use a highly effective contraceptive * Has advanced chronic kidney disease (CKD stage 3: eGFR ≥30 to \<60 mL/min, and severe renal impairment (eGFR \<30 ml/min, CKD stage 4-5) * Has severe hepatic impairment, or requires a live viral vaccine within the next seven days * Has a significant impaired immunity (e.g., due to long-term oral steroids, chemotherapy, or an immune disorder) * Requires immediate antiviral treatment or hospitalization as per the clinician's judgment * Is allergic to trial medications * Is scheduled for elective surgery or procedures requiring general anesthesia within the next two weeks * Is co-infected with viruses of interest * Received a live viral vaccine within the last 14 days