Table 2.

GMT and mean fold increase (MFI) of HI and MN titers before and after a single dose of influenza vaccine.

Influenza subtype	HI				MN
	Heroin users (n = 10)	Methadone users (n = 11)	Non user controls (n = 20)	p value	Heroin users (n = 10)	Methadone users (n = 11)	Non user controls (n = 20)	p value
A/California/7/2009 (H1N1)
Prevaccine	7.6 (3.9, 14.8)	16.6 (8.0, 34.2)	10.0 (6.2, 16.2)	0.16	19.9 (10.2, 38.8)	43.04 (20.7, 98.2)	20.1 (13.0, 30.8)	0.14
Postvaccine	278.6 (93.5, 829.7)	205.9 (72.3, 586.5)	149.3 (80.9, 275.5)	0.18	416.6 (169.3, 1025.2)	643.8 (225.6, 1837.8)	283.2 (117.4, 683.6)	0.57
MFI	21.9 (9.4, 51.1)	8.2 (4.3, 15.7)	12.2 (7.3, 20.4)	0.17	8.4 (5.4, 13.2)	6.8 (3.7, 12.6)	7.2 (5.0, 10.4)	0.67
A/Victoria/210/2009 (H3N2)
Prevaccine	20.0 (7.9, 50.9)	24.2 (7.7, 75.7)	16.8 (10.1, 28.2)	0.94	66.0 (21.8, 199.9)	65.4 (21.2, 202)	46.3 (21.5, 99.9)	0.72
Postvaccine	172.8 (79.7, 374.8)	124.4 (55.1, 280.6)	121.3 (83.7, 175.7)	0.52	521.9 (233, 1128)	513.8 (176.4, 1496.3)	353.2 (195, 627)	0.25
MFI	7.3 (3.4, 15.6)	6.1 (3.6, 10.5)	7.0 (4.9, 10.0)	0.88	5.0 (3.3, 7.7)	5.3 (3.3, 8.5)	5.6 (4.3, 7.3)	0.96
B/Brisbane/60/2008
Prevaccine	5.7 (4.7, 7.1)	12.1 (5.9, 24.9)	13.2 (8.1, 21.5)	0.06	14.1 (9.3, 21.6)	20.2 (10.5, 39.1)	19.4 (10.3, 36.7)	0.44
Postvaccine	26.4 (11.7, 59.7)	29.2 (12.9, 66.1)	47.6 (31.3, 72.4)	0.36	31.9 (15.9, 64.2)	36.6 (16.4, 81.6)	54.4 (31.7, 93.2)	0.42
MFI	6.8 (4.0, 11.8)	4.2 (2.9, 6.1)	5.5 (3.9, 7.8)	0.33	3.8 (2.8, 5.1)	3.5 (2.5, 5.1)	4.3 (3.5, 5.4)	0.36

Data are geometric means (95% confidence interval), unless defined otherwise.