Table 4. Local and Systemic Adverse Events Risks With Intradermal Doses vs 15 µg Intramuscular Dose of Influenza Vaccine.

Intradermal dose	Pooled studies, No.	Risk ratio (95% CI)	I²
Local adverse events
Ecchymosis
9 µg	7	1.67 (1.12-2.48)^a	55
15 µg	9	1.06 (0.73-1.57)	0
Erythema
3 µg	3	9.62 (1.07-86.56)^a	97.2
6 µg	2	23.79 (14.42-39.23)^a	0
9 µg	14	4.56 (3.05-6.82)^a	93.9
15 µg	16	3.68 (3.19-4.25)^a	8.8
Induration
9 µg	5	3.27 (1.65-6.46)^a	95.4
15 µg	9	2.98 (2.32-3.84)^a	42.6
Pain
3 µg	4	0.34 (0.20-0.56)^a	21.9
6 µg	2	0.98 (0.38-2.49)	68.3
9 µg	12	0.95 (0.86-1.05)	34.4
15 µg	16	0.94 (0.72-1.21)	61.3
Pruritus
6 µg	2	15.22 (4.77-48.54)^a	0
9 µg	9	4.24 (3.16-5.70)^a	56.2
15 µg	6	4.01 (3.13-5.15)^a	0
Swelling
3 µg	2	20.16 (4.68-86.82)^a	51.3
9 µg	13	5.23 (3.58-7.62)^a	84.4
15 µg	12	3.47 (2.21-5.45)^a	71.9
Systemic adverse events
Arthralgia
15 µg	3	1.17 (0.39-3.53)	22.7
Chills and shivering
9 µg	7	1.24 (1.03-1.50)^a	0
15 µg	10	1.08 (0.78-1.51)	0
Fever
6 µg	2	0.54 (0.17-1.71)	34.5
9 µg	11	1.36 (1.03-1.80)^a	0
15 µg	13	0.89 (0.59-1.34)	0
Headache
3 µg	2	1.09 (0.86-1.37)	0
6 µg	2	0.83 (0.39-1.78)	68
9 µg	13	1.03 (0.96-1.11)	0
15 µg	9	1.16 (0.94-1.45)	0
Malaise
9 µg	7	1.05 (0.94-1.20)	7.1
15 µg	14	0.97 (0.78-1.22)	0
Myalgia
9 µg	12	1.24 (0.93-1.65)	74.8
15 µg	9	0.84 (0.63-1.12)	29.4
Nausea
9 µg	3	0.93 (0.37-2.31)	0
15 µg	2	1.05 (0.33-3.33)	0

^{^a}

P < .05.