TABLE 4.

Association between COVID‐19 vaccines and hematological abnormalities in SCCS analysis

Risk period	Event	Person‐years	IR	IRR a (95% CI)
Thrombocytopenia
CoronaVac
Control period	9371	4109.18	2.28
1st dose, day 0–13	103	39.38	2.62	1.04 (0.80–1.34)
1st dose, day 14–27	116	37.70	3.08	1.18 (0.93–1.50)
2nd dose, day 0–13	80	27.49	2.91	1.08 (0.80–1.46)
2nd dose, day 14–27	67	24.94	2.69	0.92 (0.68–1.25)
BNT162b2
Control period	9287	4060.01	2.29
1st dose, day 0–13	80	32.74	2.44	0.96 (0.72–1.28)
1st dose, day 14–27	59	21.62	2.73	1.00 (0.74–1.35)
2nd dose, day 0–13	75	22.07	3.40	1.19 (0.89–1.59)
2nd dose, day 14–27	45	19.11	2.35	0.79 (0.56–1.12)
Leukopenia
CoronaVac
Control period	3787	1658.28	2.28
1st dose, day 0–13	50	18.49	2.70	1.01 (0.69–1.47)
1st dose, day 14–27	46	17.26	2.67	0.90 (0.61–1.31)
2nd dose, day 0–13	33	12.42	2.66	0.95 (0.61–1.46)
2nd dose, day 14–27	30	11.33	2.65	0.90 (0.58–1.39)
BNT162b2
Control period	3838	1698.75	2.26
1st dose, day 0–13	64	21.75	2.94	1.22 (0.87–1.72)
1st dose, day 14–27	39	14.64	2.66	1.05 (0.72–1.52)
2nd dose, day 0–13	81	15.08	5.37	2.21 (1.59–3.08)
2nd dose, day 14–27	29	13.25	2.19	0.91 (0.58–1.42)
Neutropenia
CoronaVac
Control period	756	329.56	2.29
1st dose, day 0–13	12	3.19	3.76	1.31 (0.59–2.89)
1st dose, day 14–27	4	3.07	1.30	0.50 (0.18–1.37)
2nd dose, day 0–13	5	2.17	2.30	0.92 (0.33–2.52)
2nd dose, day 14–27	4	1.99	2.01	0.69 (0.22–2.15)
BNT162b2
Control period	801	352.16	2.27
1st dose, day 0–13	12	5.47	2.19	0.41 (0.15–1.09)
1st dose, day 14–27	6	3.55	1.69	0.28 (0.10–0.85)
2nd dose, day 0–13	19	3.81	4.99	1.10 (0.52–2.31)
2nd dose, day 14–27	8	3.29	2.43	0.60 (0.25–1.46)

Abbreviations: IR, incidence rate; IRR, incidence rate ratio; SCCS, self‐controlled case series.

^a IRR was estimated using modified SCCS extension “eventdepenexp” model.