Table 5.

Summary of ELISA seroconversion rates for toxin A, toxin B, and composite response on Days 14, 30 and 60 (PP set).

	C. difficile toxoid vaccine (N = 67)
Parameter	Overall		Seropositivea		Seronegativea		Placebo (N = 34)
Visit	%	95% CI	%	95% CI	%	95% CI	%	95% CI
Toxin A IgG
Day 14	49.3	36.8;61.8	90.9	58.7;99.8	41.1	28.1;55.0	0	0.0;10.3
Day 30	94.0	85.4;98.3	100	71.5;100.0	92.9	82.7;98.0	0	0.0;10.3
Day 60	100	94.6;100.0	100	71.5;100.0	100	93.6;100.0	0	0.0;10.3
Toxin B IgG
Day 14	46.3	34.0;58.9	82.9	66.4;93.4	6.3	0.8;20.8	0	0.0;10.3
Day 30	83.6	72.5;91.5	97.1	85.1;99.9	68.8	50.0;83.9	0	0.0;10.3
Day 60	97.0	89.6;99.6	97.1	85.1;99.9	96.9	83.8;99.9	0	0.0;10.3
Composite responseb
Day 14	37.3	25.8;50.0	90.9	58.7;99.8	3.1	0.1;16.2	0	0.0;10.3
Day 30	80.6	69.1;89.2	100	71.5;100.0	65.6	46.8;81.4	0	0.0;10.3
Day 60	97.0	89.6;99.6	100	71.5;100.0	96.9	83.8;99.9	0	0.0;10.3

^aParticipants who were seropositive by ELISA (N = 11 and 35 for toxins A and B, respectively) or seronegative by ELISA (N = 56 and 32 for toxins A and B, respectively) at baseline.

^bComposite response indicates a ≥4-fold increase for both toxins.