Rate ratio of sudden unexpected deaths in infants of age 31–729 days for the risk period 0–14 days following vaccination with a combination of six antigens by dose, Italy 1999–2004.

N: Number of deaths; P-d: Person-days at risk; RR adj: adjusted Rate Ratio; CI: Confidence Interval.1RRs are estimated by the Poisson regression model and adjusted by age group (31–80; 81–100; 101–120; 121–180; 181–360; 361–729 for the first dose; 31–180; 181–360; 361–729 for the second-third dose).2The information on the brand name of the hexavalent product was missing for 1 infant (the event occurred in the control period).