Table 3.

Inactivated influenza vaccine effectiveness against hospitalization with influenza-associated ALRI, July–December 2010 and 2011, (N = 1545)

	Unadjusted VE	95% CI		Adjusted VE	95% CI
2010 and 2011 seasons	43%	0	68	47*	5	71
Sensitivity analyses
2010 season**	35	−7	75	17	−127	70
2011 season**	47	−7	74	52	−1	77
2010 and 2011 seasons adjusting for time as
month and year of circulation***	–	–	–	45	0	70

^*Adjusted for age, presence of ≥1 underlying medical conditions, time as peak versus non-peak influenza virus circulation, and province.

^**Season defined as July–December of each year.

^***Instead of peak versus non-peak influenza virus circulation.