Table 3. RI of infection by the SCCS method (adjusted for time period (4 weekly period)) for hospital admitted patients with myocarditis or pericarditis aged 12+ years who tested positive for SARS-CoV-2 infection.

Interval from test to admission	Type of infection		Vaccination status		Variant
	First	Reinfection	Unvaccinated^	Vaccinated ≥1 dose	Alpha	Delta	Omicron
Day 0
Number cases	50	4	19	35	3	29	22
Person years	3.1	0.9	1	3.1	0.3	2.3	1.4
RI (95% CIs)	17.29	4.75	24.66	11.98	13.96	13.18	16.79
	(12.96, 23.00)	(1.77, 12.80)	(15.42, 39.44)	(8.39, 16.59)	(4.37, 46.64)	(9.06, 19.17)	(10.83, 26.01)
	p < 0.001	p = 0.002	p < 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001
Days 1–27
Number cases	193	50	71	172	27	150	66
Person years	82.4	22.5	27	77.8	10.8	62.1	32
RI (95% CIs)	2.57	2.49	3.32	2.33	3.13	2.58	2.34
	(2.19, 3.01)	(1.82, 3.41)	(2.54, 4.33)	(1.96, 2.76)	(2.02, 4.84)	(2.15, 3.1)	(1.77, 3.1)
	p < 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001

^{^} Includes infections before the first dose.

CI, confidence interval; RI, relative incidence; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2; SCCS, self-controlled case series.