Difference in immune response in vaccinated and unvaccinated Swedish individuals after the 2009 influenza pandemic

Table 2 Mean values of A/H1N1/California/7/2009-specific Abs (measured by SRH) and IFN-γ production in the whole-blood assay before (A) and after (C) the 2009/2010 flu season in study participants with our without pdm flu vaccination

Time point	A		C		A	C
	pdm vaccination
	Vacc.	Not vacc.	Vacc.	Not vacc.	V/NV¹-diff.
	SRH (mm²), geometric mean
A/H1N1/California	20.1 (18.5–21.8)	19.3 (17.3–21.4)	27.9 (26.4–29.5)	20.7 (18.9–22.6)	0.3	*<0.001*
	IFN-γ (pg/mL), mean
A/H1N1/Brisbane	139	133	285	169	0.3	*<0.001*
A/H1N1/Solomon	119	113	246	151	0.2	*<0.001*
A/H3N2/Uruguay	194	177	304	238	0.2	*<0.001*
A/H3N2/Wisconsin	203	195	301	251	0.6	*<0.01*
A/H5N1/Vietnam	346	352	423	373	0.6	*<0.01*
B/Florida	221	250	245	283	0.1	*0.04*
B/Malaysia	145	168	167	200	0.15	0.07
M1	33	34	63	34	0.8	*<0.01*
M2	18	18	20	20	0.4	0.8
CFP-10	21	21	24	22	0.7	0.2
PHA	501	513	506	545	0.13	0.02
N	437	232	437	232
Mean age, years	47	41	47	41	<0.001	<0.001

The Wilcoxon-Mann–Whitney rank-sum test was used to calculate p-values. ¹V/NV: vaccinated vs. unvaccinated. Listed are Ab responses (top panel, directed against A/H1N1 California, mean and confidence interval) and IFN-γ responses directed against a broad panel of flu targets (designated the flu A or flu B strains), and against matrix proteins M1 and M2. CFP10 served as control. PHA was the positive control stimulus. P values below 0.05 are indicated in bold.

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