Table 4. Protective effect of a first typhoid visit against recurrent typhoid due to reinfection in the non-Vi vaccinated population including in-migrants post-vaccination (n = 47,995).

	No. of individuals	No. of typhoid visits	Person-days †	Incidence per 100,000 person-days	Crude HR ‡	Adjusted Protective Efficacy (95% CI) ‡
Cohort 1	47995	149	32868952	0.45	Ref	Ref
All recurrent typhoid visits
Cohort 2	149	1	108912	0.92	4.21 (0.59, 30.13)	-88% (-1246, 74)
Recurrent typhoid due to reinfection defined by strain§
Cohort 2	149	1	108912	0.92	4.21 (0.59, 30.13)	-88% (-1246, 74)
Recurrent typhoid due to reinfection defined by antibiotic susceptibility∥
Cohort 2	149	1	108912	0.92	4.21 (0.59, 30.13)	-88% (-1246, 74)
Recurrent typhoid due to reinfection defined by interval ¶
Cohort 2	147	0	109540	0	--	--

†In cohort 1, person-days calculated from zero time (date of vaccination with placebo or for non-dosed individuals, the median zero time for the cluster of residence at the time of vaccination, or date of entry for in-migrants post-vaccination) to end date, which is defined as date of study end, out-migration, or onset of the first typhoid visit. In cohort 2, person-days are calculated from the date of first typhoid visit to the date of study end, out-migration, death, or onset of the subsequent typhoid visit.

‡ Fitted a generalized proportional hazard model (AG model). The number of previous infections (0 or 1) was included in the model as a dummy variable; the reference group was the group with no previously detected typhoid visit. The hazard ratio was adjusted for age at date of entry.

§ Pairwise SNP difference >5

∥ Discordance in antibiotic susceptibility between infection pair >0

¶ Intervening period >30 days