Table 3.

Age-specific SIRs (95% CIs) of myo/pericarditis in the 21 days following the first and second dose of the BNT162b2 vaccine, stratified by 20-year age group, 19 February 2021–10 February 2022, New Zealand

Vaccine dose	Age group, years	No. of participants	Person days	Observed events	Expected eventsa	SIR (95% CI)	Risk difference (95% CI) [per 100,000 persons]
First dose	5–19	698,110	14,073,857	12	≤6	9.8 (4.6–15.9)	1.6 (0.7 to 2.7)
	20–39	1,315,494	28,872,988	41	11.5	3.5 (2.5–4.7)	2.1 (1.3 to 3.1)
	40–59	1,194,979	26,262,889	30	14.6	2.1 (1.4–2.8)	1.2 (0.4 to 2.1)
	60–79	864,098	19,004,002	16	14.4	1.1 (0.6–1.7)	0.2 (−0.6 to 1.1)
	≥80	182,447	4,006,245	≤6b	≤6	0.8 (0.0–2.1)	−0.3 (−1.4 to 1.4)
	Total	4,255,128	92,219,981	101	44.2	2.3 (1.8–2.7)	1.3 (0.9 to 1.8)
Second dose	5–19	468,104	10,191,896	23	≤6	25.6 (15.5–37.5)	4.6 (2.7 to 6.6)
	20–39	1,286,717	28,158,738	74	11.3	6.6 (5.1–8.2)	4.7 (3.5 to 6.0)
	40–59	1,180,519	25,908,681	49	14.4	3.4 (2.5–4.4)	2.8 (1.7 to 4.0)
	60–79	86,2146	18,947,465	22	14.3	1.5 (0.9–2.2)	0.8 (−0.1 to 1.9)
	≥80	181,950	3,992,858	≤6	≤6	1.6 (0.4–3.4)	0.8 (−0.9 to 3.0)
	Total	3,979,436	87,199,638	172	43.4	4.0 (3.4–4.6)	3.1 (2.5 to 3.7)

SIR standardised incidence ratio, CI confidence interval, COVID-19 coronavirus disease 2019, AESI adverse events of special interest

^aExpected events were calculated using background incidence rates from the SAFE background rate study of COVID-19 AESIs in New Zealand (2014–2019) [27] and person time at risk

^bEvents with fewer than six occurrences have been suppressed for privacy reasons