Table 4.

Effect of influenza vaccination status in the current and 5 prior seasons in preventing laboratory-confirmed influenza in the target population for influenza vaccination^a with and without chronic obstructive pulmonary disease.

	Cases/controls	Adjusted odds ratio (95% CI)b	p value
All patients
Target population without COPD unvaccinated	776/866	1
Target population without COPD vaccinated in prior seasons only	196/408	0.64 (0.52–0.79)	< 0.001
Target population without COPD vaccinated in the current season	833/1829	0.60 (0.51–0.69)	< 0.001
Patients with COPD unvaccinated	154/215	1
Patients with COPD vaccinated in prior seasons only	79/172	0.75 (0.53–1.08)c	0.120
Patients with COPD vaccinated in the current season	309/832	0.61 (0.47–0.79)c	< 0.001
Primary healthcare patients
Target population without COPD unvaccinated	348/167	1
Target population without COPD vaccinated in prior seasons only	35/28	0.52 (0.30–0.91)	0.022
Target population without COPD vaccinated in the current season	169/161	0.49 (0.34–0.68)	< 0.001
Patients with COPD unvaccinated	54/30	1
Patients with COPD vaccinated in prior seasons only	5/7	0.48 (0.13–1.75)c	0.264
Patients with COPD vaccinated in the current season	33/35	0.45 (0.22–0.92)c	0.029
Hospital patients
Target population without COPD unvaccinated	428/699	1
Target population without COPD vaccinated in prior seasons only	161/380	0.67 (0.53–0.84)	0.001
Target population without COPD vaccinated in the current season	664/1668	0.63 (0.53–0.74)	< 0.001
Patients with COPD unvaccinated	100/185	1
Patients with COPD vaccinated in prior seasons only	74/165	0.78 (0.53–1.14)c	0.201
Patients with COPD vaccinated in the current season	276/797	0.63 (0.47–0.84) c	0.002

CI confidence interval, COPD chronic obstructive pulmonary disease.

^aTarget population for influenza vaccination included people ≥ 60 years or with major chronic conditions.

^bOdds ratio adjusted by age groups (25–64, 65–84 and ≥ 85 years), other major chronic conditions, healthcare setting (primary healthcare or hospital), and month-season of sample collection.

^cComparison of the adjusted odds ratios in COPD vs. non-COPD patients: all patients with current season vaccination, p = 0.339; all patients with vaccination in prior seasons only, p = 0.712; outpatients with current season vaccination, p = 0.468; outpatients with vaccination in prior seasons only, p = 0.745; inpatients with current season vaccination, p = 0.345; inpatients with vaccination in prior seasons only, p = 0.701.