Influenza vaccine effectiveness assessment through sentinel virological data in three post-pandemic seasons

Figures & data

Table 1. Distribution according to influenza season of number of samples with available information and percentage of vaccinated cases. Catalonia, 2010–2013

Season	Number of samples with immunization record	Number of samples with no immunization record	OR (95%CI) P value
2010–2011	1117	154 (12.1%)	0.83(0.64–1.07) 0.16
2011–2012	1092	125 (10.3%)	ref
2012–2013	964	157 (14%)	0.70(0.54–0.91) 0.006

OR, odds ratio; CI, confidence interval.

Figure 1. Evolution of ILI activity for the three influenza seasons 2010-2011, 2011-2012 and 2012-2013. Catalonia, Spain

Table 2. Distribution according to influenza season of samples with available information and percentage of vaccinated and unvaccinated patients. Catalonia, 2010–2013

Season	Vaccinated patients	Not vaccinated patients	OR (95%CI) P value
2010–2011	165/ (13%)	952 (87.9%)	0.98 (0.76–1.26) 0.92
2011–2012	159/ (13.1%)	933 (89.7%)	0.99 (0.77- 1.28) 0.97
2012–2013	140/ (12.5%)	824 (86%)	ref

OR, odds ratio; CI, confidence interval.

Table 3. Distribution of vaccination coverage in two different sources of information according to age group in ILI cases sampled with at least one risk factor for complications. Catalonia, 2010–2013

	Age group
Population studied	0–14 y	15–59 y	60 y or more
Recorded at SISAP (for at risk population in Catalonia)	32.47%*	21.01%	52.82%**
Sentinel practitioners (for at risk population sampled)	48.8%*	26.5%	65.5%, 72.8%**(with RF)

* P = 0.02, **P = 0.005; SISAP, Information System for Primary Health Care Centers; RF, Risk factor.

Table 4. Vaccine effectiveness for influenza vaccines in three epidemic seasons. Catalonia, 2010–2013

Season (predominant influenza virus)	Number of ILI samples	Number of positive IV samples/Negative IV samples	Number of vaccinated positive IV /total positive IV (% vaccinated) vaccinated negative IV/total negative samples (% vaccinated)	Vaccine effectiveness (95%CI)
2010–2011 [A(H1N1)pdm09]	1117	383/734	27/383 (7.2%), 138/734 (13.6%)	67.2% (49.5–78.8%)
2011–2012 [A(H3N2)]	1092	387/705	44/387 (11.4%), 115/705 (16.3%)	34.2% (4.5–54.6%)
2012–2013 (B)	964	347/617	23/347 (6.6%), 117/617 (19%)	69.7% (51.5–81%)
Total	3173	1117/2056	94/1117 (8.4%), 370/2056 (18%)	58.1% (46.8–67%)