This protocol is a prospective, multi-center, multi-arm, randomized, controlled platform trial evaluating various interventions for use in the treatment of autonomic dysfunction symptoms, including cardiovascular complications and postural orthostatic tachycardia syndrome (POTS), in PASC participants. The interventions tested will include non-pharmacologic care and pharmacologic therapies with study drugs. conditions: Long COVID conditions: Long Covid19 conditions: Long Covid-19 studyType: INTERVENTIONAL phases: PHASE2 allocation: RANDOMIZED interventionModel: PARALLEL interventionModelDescription: In each Appendix trial, each participant will be assigned with equal probability to one of the factorial combinations based on two factors: (1) a study intervention/control and (2) non-pharmacologic intervention/control if the participant is eligible for the study intervention. primaryPurpose: TREATMENT masking: TRIPLE maskingDescription: Double blind whoMasked: PARTICIPANT whoMasked: CARE_PROVIDER whoMasked: INVESTIGATOR count: 380 type: ESTIMATED name: IVIG + Coordinated Care name: IVIG Placebo + Coordinated Care name: Ivabradine + Coordinated Care name: Ivabradine Placebo + Coordinated Care name: IVIG + Usual Care name: IVIG Placebo + Usual Care name: Ivabradine + Usual Care name: Ivabradine Placebo + Usual Care measure: Change in Orthostatic Hypotension Questionnaire (OHQ)/Orthostatic Intolerance Questionnaire (OIQ) Composite Score measure: Change in Composite Autonomic Symptoms Score 31 (COMPASS-31) measure: Change in Malmo POTS Symptom Score measure: Change in Active Stand Test measure: Change in blood pressure measure: Change in heart rate (HR) measure: Change in 6-min Walk Test measure: Change in PROMIS-29 + 2 Questionnaire measure: Change in step count as measured by a wearable device measure: Change in heart rate as measured by a wearable device measure: Proportion of participants who experience individual SAEs measure: Proportion who experience any one or more SAEs measure: Incidence of SAEs leading to discontinuation measure: Incidence of Events of Special Interest (ESIs) measure: Changes in Autonomic Function Testing measure: Change in Vanderbilt Orthostatic Symptoms Score (VOSS) measure: Change in PASC Symptom Questionnaire sex: ALL minimumAge: 18 Years stdAges: ADULT stdAges: OLDER_ADULT facility: University of Colorado Anschutz Medical Campus Clinical and Translational Research Center (CTRC) - Appendix A & B city: Aurora state: Colorado zip: 80045 country: United States lat: 39.72943 lon: -104.83192 facility: Rush University Medical Center - Appendix A & B city: Chicago state: Illinois zip: 60612 country: United States lat: 41.85003 lon: -87.65005 facility: NorthShore University HealthSystem - Evanston Hospital - Appendix B Only city: Evanston state: Illinois zip: 60201 country: United States lat: 42.04114 lon: -87.69006 facility: University of Kansas Medical Center CTSU Fairway - Appendix A & B city: Fairway state: Kansas zip: 66205 country: United States lat: 39.02223 lon: -94.6319 facility: St. Lawrence Health Medical Campus - Appendix A & B city: Canton state: New York zip: 13617 country: United States lat: 44.59562 lon: -75.16909 facility: Sentara Norfolk General Hospital - Appendix A and B city: Norfolk state: Virginia zip: 23507 country: United States lat: 36.84681 lon: -76.28522 facility: Providence Medical Research Center - Appendix A & B city: Spokane state: Washington zip: 99204 country: United States lat: 47.65966 lon: -117.42908 hasResults: False