. 2021 Jun 9;27(7):1290–1297. doi: 10.1038/s41591-021-01408-4

Table 3.

Observed versus expected thrombocytopenia and ITP events after COVID-19 vaccination

Age group	Number study individuals vaccinated	Thrombocytopenia (excluding ITP)			ITP
Age group	Number study individuals vaccinated	Observed events^a	Expected number of events^b	Observed–expected (95% CI)^c	Observed events^a	Expected number of events^b	Observed–expected (95% CI)^c
ChAdOx1
16–39	181,635	≤5^d	≤5^d	1.17 (−1.83–5.13)	≤5^d	≤5^d	2.62 (−0.38–6.62)
40–59	740,800	22	14.3	7.71 (−2.71–18.63)	6	1.4	4.58 (0.10–10.05)
60–79	606,854	49	40.6	8.41 (−10.08–27.10)	14	7.1	6.85 (−2.23–15.96)
80+	178,673	32	26.6	5.40 (−12.89–23.00)	5	11.3	−6.26 (−16.76–3.25)
BNT162b2
16–39	144,393	7	3.8	3.23 (−1.85–9.30)	≤5^d	≤5^d	1.20 (−1.13–4.47)
40–59	230,802	6	13.0	−7.00 (−13.59–0.07)	≤5^d	≤5^d	(−0.33(−2.66–2.23)
60–79	409,429	27	34.2	−7.24 (−21.63–7.54)	≤5^d	≤5^d	−2.05 (−8.24–3.81)
80+	36,428	≤5^d	≤5^d	−3.38 (−8.02–1.53)	0	2.7	−2.70 (−4.96–0.90)

^aThe observed events were incident cases after vaccination counted for the observed duration of the post-vaccination period. ^bThe expected events are the number of events per day in the pre-vaccination period divided by the population and multiplied by the days at risk in the post-vaccination period for all vaccinated and then summed. ^cThe difference between expected (the number of events per day in the pre-vaccination period divided by the population and multiplied by the days at risk in the post-vaccination period for all vaccinated and then summed) and observed events during the post-vaccination period, with CIs obtained from a parametric bootstrap, was based on the Poisson distribution using 10,000 samples. There was limited opportunity for matching in this analysis, and the findings, therefore, need to be interpreted with caution. ^dn ≤ 5 denotes minimum allowable reported value.