Table 1.

Inclusion and exclusion criteria for Step 1 and Step 2

	Step 1	Step 2
Inclusion criteria	Ages 1 month to 18 years	As in Step 1
	Diagnosis of Kawasaki disease: 5 days of fever and 4 out of 5 symptoms (conjunctival injection, palmar or solar edema, cervical lymphadenopathy, lingual or labial erythema, maculopapular rash)
	Diagnosis and hospitalization within 3 weeks of fever onset
	Informed consent (and assent)
		Coronary artery dilation with a z-score ≥ 2.5
Exclusion criteria	Denial of consent/assent	As in Step 1
	Fever onset more than 3 weeks prior to diagnosis and hospitalization
		Tetracycline or sulfite allergy or prior treatment with tetracyclines (< 8 years of age)
		Kidney failure (creatinine level above the upper limit of normal for age)
		Liver failure (AST, ALT, bilirubin or GGT level elevated 5x above the upper limit of normal for age)