Effectiveness of the trivalent influenza vaccine in Navarre, Spain, 2010–2011: a population-based test-negative case–control study

Table 3 Estimates of the effect of the 2010–2011 seasonal influenza vaccine and monovalent influenza A(H1N1)pdm09 vaccine in preventing laboratory-confirmed influenza, Navarre, Spain 2010–2011

	Case/control	Crude vaccine effectiveness, % (95% CI) ^a	P-value	Adjusted vaccine effectiveness, % (95% CI) ^b	P-value
All swabbed patients
Seasonal and pandemic vaccines	2 / 19	91 (63; 98)	0.001	87 (30; 98)	0.017
Only seasonal vaccine	11 / 26	65 (28; 83)	0.004	64 (14; 85)	0.022
Only pandemic vaccine	4 / 7	53 (−62; 86)	0.230	21 (−252; 82)	0.755
Unvaccinated	286 / 234	Ref.		Ref.
Influenza A(H1N1)pdm09 cases vs. controls
Seasonal and pandemic vaccines	2 / 19	91 (57; 98)	0.002	86 (25; 97)	0.022
Only seasonal vaccine	11 / 26	61 (18; 81)	0.012	60 (2; 83)	0.044
Only pandemic vaccine	3 / 7	60 (−56; 90)	0.187	53 (−132; 91)	0.351
Unvaccinated	251 / 234	Ref.		Ref.
Subjects with indication for seasonal vaccination
Seasonal and pandemic vaccines	2 / 16	89 (50; 97)	0.004	81 (−9; 97)	0.062
Only seasonal vaccine	10 / 21	58 (3; 81)	0.041	50 (−38; 82)	0.179
Only pandemic vaccine	4 / 5	29 (−176; 82)	0.623	−32 (−694; 78)	0.763
Unvaccinated	72 / 64	Ref.		Ref.

^a Logistic regression model including 2010–2011 seasonal and monovalent A(H1N1)pdm09 influenza vaccination status as a combined variable (unvaccinated, only seasonal vaccine, only pandemic vaccine, or both vaccines).
^b Logistic regression model including 2010–2011 seasonal and monovalent A(H1N1)pdm09 influenza vaccination status as a combined variable (unvaccinated, only seasonal vaccine, only pandemic vaccine, or both vaccines) and adjusted for sex, age, major chronic conditions, outpatient visits in the previous year, swabbing within 4 days of symptom onset, health care setting and period.

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