Table 3.

Individual-level protection against typhoid associated with “Better” household WASH^a in the total population residing in the control clusters of the Vi-TT^b cluster randomized trial, Dhaka, Bangladesh, stratified by age at onset of follow-up.

Years	“Better” WASH					“Not Better” WASH					Hazard ratio (HRc)d
	ne	Cases	PYf	IRg/100,000 PY	N		Cases	PY	IR/100,000 PY	Crude HRh		P valueh	Adjusted HRh,i	P valueh
All	56,969	110	79,326	139	106,404		325	129,088	252	0.56 (0.44,0.71)		<.001	0.62 (0.49-0.78)	<.001
<2 years	3356	13	3883	335	6979		45	7211	624	0.54 (0.28,1.06)		.08	0.65 (0.32-1.28)	.21
2-4 years	3131	18	4424	407	6438		93	7919	1174	0.35 (0.22,0.57)		<.001	0.35 (0.20-0.61)	<.001
5-9 years	4894	26	7086	367	9819		84	12,586	667	0.57 (0.35,0.94)		.03	0.58 (0.36-0.92)	.02
10-14 years	4997	20	7278	275	9265		38	12,123	313	0.88 (0.5,1.56)		.66	0.92 (0.53-1.59)	.77
>15 years	40,591	33	56,655	58	73,903		65	89,250	73	0.76 (0.48,1.21)		.25	0.79 (0.50-1.24)	.31

^aWASH: water, sanitation, and hygiene.

^bVi-TT: Vi-tetanus toxoid.

^cHR: hazard ratio.

^dHazard ratios are estimated from extended Cox proportional hazards model.

^en: number; 100K: 100,000.

^fPY: person years.

^gIR: incidence rate.

^hP values and CI are calculated using robust SE assuming risk of typhoid is correlated within clusters.

ⁱHazard ratio adjusted for the stratifying variables for randomization, including geographic ward, longer distance to study clinics than median distance, number of eligible children at baseline, and other baseline covariates age, Muslim religion; total monthly income; number of participants in a cluster.