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

Martínez-Baz, Iván; Martínez-Artola, Víctor; Reina, Gabriel; Guevara, Marcela; Cenoz, Manuel García; Morán, Julio; Irisarri, Fátima; Arriazu, Maite; Albeniz, Esther; Castilla, Jesús

doi:10.1186/1471-2458-13-191

Table 2 Influenza vaccine effectiveness in preventing laboratory-confirmed influenza in the 2010–2011 season in Navarre, Spain

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

	Cases/controls	Crude vaccine effectiveness, % (95% CI)	p-value	Adjusted vaccine effectiveness, % (95% CI)	p-value
All swabbed patients
Pandemic vaccine 2009-2010
No	297/260	Ref.		Ref.
Yes	6/26	80 (50; 92)	<0.001	45 (−68; 82) ^a	0.297
Seasonal vaccine 2010-2011
No	290/241	Ref.		Ref.
Yes	13/45	76 (54; 87)	<0.001	67 (24; 86) ^a	0.009
Patients swabbed within 4 days of symptom onset
Pandemic vaccine 2009-2010
No	292/250	Ref.		Ref.
Yes	6/25	79 (49; 92)	0.001	44 (−71; 82) ^a	0.309
Seasonal vaccine 2010-2011
No	286/235	Ref.		Ref.
Yes	12/40	75 (52; 87)	<0.001	65 (16; 85) ^a	0.018
Influenza A(H1N1)pdm09 cases vs. controls
Pandemic vaccine 2009-2010
No	262/260	Ref.		Ref.
Yes	5/26	81 (49; 93)	<0.001	60 (−30; 87) ^a	0.129
Seasonal vaccine 2010-2011
No	254/241	Ref.		Ref.
Yes	13/45	73 (48; 86)	<0.001	61 (9; 83) ^a	0.030
Influenza B cases vs. controls
Seasonal vaccine 2010-2011
No	33/241	Ref.		Ref.
Yes	0/45	89 (33; 100)^c	0.010	93 (36; 100) ^c,d	0.017
Subjects with indication for seasonal vaccination ^b
Pandemic vaccine 2009-2010
No	82/85	Ref.		Ref.
Yes	6/21	70 (24; 89)	0.013	28 (−147; 79) ^a	0.599
Seasonal vaccine 2010-2011
No	76/69	Ref.		Ref.
Yes	12/37	71 (39; 86)	0.001	64 (8; 86) ^a	0.034
Primary health care patients
Pandemic vaccine 2009-2010
No	286/227	Ref.		Ref.
Yes	4/13	76 (24; 92)	0.015	56 (−70; 89) ^e	0.231
Seasonal vaccine 2010-2011
No	280/216	Ref.		Ref.
Yes	10/24	68 (31; 75)	0.003	68 (17; 87) ^e	0.019
Hospitalized patients
Pandemic vaccine 2009-2010
No	11/33	Ref.		Ref.
Yes	2/13	54 (−137; 91) ^c	0.355	8 (−967; 94) ^c,e	1.000
Seasonal vaccine 2010-2011
No	10/25	Ref.		Ref.
Yes	3/21	64 (−47; 91) ^c	0.154	61 (−316; 98) ^c,e	0.677
Subjects aged less than 50 years
Pandemic vaccine 2009-2010
No	246/191	Ref.		Ref.
Yes	2/6	74 (−30; 95)	0.100	60 (−65; 94) ^a	0.341
Seasonal vaccine 2010-2011
No	245/188	Ref.		Ref.
Yes	3/9	75 (4; 93)	0.043	73 (−21; 94) ^a	0.086
Subjects aged 50 years or older
Pandemic vaccine 2009-2010
No	51/69	Ref.		Ref.
Yes	4/20	73 (26; 91)	0.024	47 (−133; 88) ^a	0.401
Seasonal vaccine 2010-2011
No	45/53	Ref.		Ref.
Yes	10/36	67 (27; 85)	0.007	69 (0; 91) ^a	0.050

CI confidence interval.
^a Estimates obtained by a logistic regression model including 2010–2011 seasonal and monovalent A(H1N1)pdm09 influenza vaccination, 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.
^b Indication for vaccination includes people age ≥60 years old and people with major chronic conditions.
^c Estimates obtained by exact logistic regression.
^d Estimates obtained by a logistic regression model including 2010–2011 seasonal influenza vaccination, 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.
^e Estimates obtained by a logistic regression model including 2010–2011 seasonal and monovalent A(H1N1)pdm09 influenza vaccination, and adjusted for sex, age, major chronic conditions, outpatient visits in the previous year, swabbing within 4 days of symptom onset and period.

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