Enrolment			Post-allocation		Close-out
			After consent	After randomisation	Treatment	14 weeks after randomisation	26 weeks after randomisation
Timepoint:			Baseline			Post-treatment	Follow-up
Enrolment	Eligibility screen	X
	Informed consent	X
	Allocation			X
	Demographic information		X
Interventions	OSI				X
	C-TAU				X
Assessments
Child report
Symptom measure	RCADS-C		X			X	X
Functional impairment	CAIS-C		X			X	X
Adverse Events	AE Self-report					X	X
Parent report
Symptom measures	RCADS-P		X			X	X
	SCAS-P-8		X			X	X
Functional impairment	CAIS-P		X			X	X
	ORS		X			X	X
Co-morbid problems	SDQ-P		X			X	X
Pandemic Anxiety Scale	PAS		X			X	X
Treatment acceptability	Credibility and Expectation of Improvement scale			X		X
Adverse events	AE Self-report					X	X
Health economics	CSRI		X			X	X
	EQ-5D-5L- P		X			X	X
	CHU-9D (YP proxy)		X			X	X
	CAIS-P		X			X	X
OSI+therapist support ARM ONLY Measures collected during treatment (parent only)	RCADS-P				X
	SCAS-P-8				X
	CAIS-P				X
	ORS				X
	SRS				X
	GBOs				X
Qualitative interviews						X (subgroup of participants interviewed once each between 14 and 26 weeks).
Therapist Logs					X	X	X