Table 1.

Standardized incidence ratio (SIR), attributable risk fraction (ARF), and attributable risk (AR) for the first vaccine dose, stratified by sex and age groups.

Sex and age group (years)	Vaccinated with the first dose1(n)	Observed cases2(n)	Risk per 100,000 vaccinees3	Expected cases (2019 reference)4(n)	SIR5 (95% CI)	ARF6	AR per 100,000 vaccinees7
All8	2594990	132	5.09	97.10	1.36 (1.14-1.61)	0.26	1.35
Males(n=1,256,958)
16-44	654040	22	3.36	20.81	1.06 (0.68-1.57)	0.06	0.19
45-64	339849	23	6.77	21.44	1.07 (0.70-1.58)	0.07	0.44
65+	263069	17	6.46	12.72	1.34 (0.80-2.10)	0.25	1.64
Females(n=1,338,032)
16-44	659597	24	3.64	19.67	1.22 (0.80-1.79)	0.18	0.66
45-64	354617	22	6.20	12.89	1.71 (1.10-2.54)	0.42	2.58
65+	323818	24	7.41	9.56	2.51 (1.65-3.68)	0.60	4.46

¹Number of those who received the first vaccine dose between 20 December 2020 and 30 April 2021

²Number of observed cases of Bell's palsy that occurred within 21 days after the receipt of the first dose

³The risk of Bell's palsy within 21 days after the first vaccine dose, estimated by dividing the number of observed cases by the number of vaccinees and reported per 100,000 vaccinees

⁴Expected number of cases of Bell's palsy as estimated based on the experience of CHS population between January-May 2019

⁵Standardized incidence ratio (SIR), computed by dividing the observed cases by the expected cases of Bell's palsy.

⁶Attributable risk fraction (ARF) among exposed (vaccinated), calculated as (SIR-1)/SIR

⁷Attributable risk (AR) per 100,000 vaccinees, estimated by multiplying ARF by the risk of Bell's palsy among vaccinated.

⁸Age and sex weighted