Table 2. Seroconversion, Seroprotection, and GMT of Intradermal Doses vs Standard 15-μg Intramuscular Dose of Influenza Vaccine.

Intradermal dose	Studies, No.	Risk ratio (95% CI)	I²
Seroconversion
H1N1
3 µg	2	1.77 (0.43-7.28)	82.6
6 µg	3	1.00 (0.78-1.28)	87.7
7.5 µg	3	1.01 (0.80-1.28)	0
9 µg	10	1.02 (0.93-1.12)	59
15 µg	16	1.10 (1.01-1.20)^a	50.5
H3N2
3 µg	2	1.14 (0.56-2.31)	81.3
6 µg	3	0.98 (0.97-1.00)	0
7.5 µg	3	0.92 (0.63-1.33)	63.8
9 µg	11	1.01 (0.95-1.06)	38
15 µg	17	1.07 (0.99-1.17)	43.2
B Strain
3 µg	2	1.46 (0.67-1.99)	53.5
6 µg	3	0.95 (0.68-1.32)	88.3
7.5 µg	3	1.21 (0.79-1.85)	43.9
9 µg	11	0.95 (0.84-1.08)	57.1
15 µg	16	1.40 (1.13-1.73)^a	59.1
Seroprotection
H1N1
3 µg	3	1.00 (0.78-1.28)	87.7
6 µg	3	0.93 (0.88-0.99)^a	37.5
7.5 µg	3	1.07 (1.01-1.12)^a	0
9 µg	12	1.00 (0.98-1.03)	33
15 µg	17	1.05 (1.01-1.09)^a	43.6
H3N2
3 µg	3	0.98 (0.97-1.00)	0
6 µg	3	1.00 (0.99-1.01)	0
7.5 µg	3	1.01 (0.96-1.06)	36.6
9 µg	12	1.00 (0.99-1.00)	0
15 µg	18	1.01 (0.99-1.02)	25.9
B Strain
3 µg	3	0.95 (0.68-1.32)	88.3
6 µg	3	0.92 (0.86-0.98)^a	0
7.5 µg	3	1.13 (0.78-1.66)	58.2
9 µg	12	0.99 (0.95-1.03)	50
15 µg	16	1.03 (0.97-1.09)	48.5
GMT^b
H1N1
3 µg	3	1.00 (0.54-1.84)	99.9
6 µg	2	0.88 (0.85-0.90)^a	65.1
9 µg	11	1.04 (0.99-1.10)	99.8
15 µg	11	1.17 (0.95-1.42)	99.9
H3N2
3 µg	3	0.90 (0.68-1.18)	99.4
6 µg	3	1.09 (0.90-1.32)	99
9 µg	11	1.08 (1.05-1.12)^a	99.4
15 µg	11	1.16 (0.96-1.41)	100
B strain
3 µg	3	0.80 (0.46-1.38)	99.9
6 µg	2	0.82 (0.67-1.01)	98.9
9 µg	11	0.93 (0.86-1.01)	99.9
15 µg	11	1.21 (1.11-1.32)^a	99.8

Abbreviation: GMT, geometric mean titer.

^{^a}

P < 05.

^{^b}

Data are expressed as ratio of means for GMT.