Table 5.

Incidence rate ratios (IRR) of hospitalization for bronchiolitis in preterm infants immunized compared to those not immunized with Palivizumab, Rome, Italy 2000-2006

	Vaccination-dose effectiveness			Vaccination-strategy effectiveness
	IRR	95% CI	p-value	IRR	95% CI	p-value
Model 1: univariate analysis	1,37	0,60 -3,11	0,45	0,82	0,40 -1,69	0,59
Model 2: multiple analysis*	0,51	0,22 -1,17	0,11	0,47	0,23 -0,98	0,04
Model 3: as model 2 but restricted to GA<32 weeks	0,67	0,24 -1,85	0,44	0,65	0,26 -1,63	0,36
Model 4: as model 2 but restricted only to the epidemic period	0,50	0,22 -1,14	0,10	0,49	0,24 -1,03	0,06

*adjusted for all covariates of table 3; GA = Gestational age