Table 3. Latent TB infection and probable/confirmed TB among students in the same grade as index case, by exposure (Zhejiang Province, China, 2009–2010).

Exposure	Total No.	No. tested	Latent TB Infection			Probable/Confirmed TB
			n	Rate (%)	RR (95% CI)	n	Rate (%)	RR (95% CI)
Same classroom as index case	46	46	26	57	2.5 (1.9–3.4)a	15	33	17 (7.8–39)a
Boys	22	22	13	54	0.92 (0.55–1.5)	10	42	1.8 (0.74–4.5)
Girls	24	24	13	59	Ref	5	23	Ref
Different classroom from index caseb	430	428	96	22	Ref	8	1.9	Ref
Boys	227	225	40	18	0.64 (0.45–0.92)	5	2.2	1.5 (0.36–6.2)
Girls	203	203	56	28	Ref	3	1.5	Ref
Residential status
Boarding	235	233	63	32	1.1 (0.81–1.4)	11	4.7	0.95 (0.43–2.1)
Commuting	241	241	59	29	Ref	12	4.9	Ref

Abbreviations: RR, rate ratio; TB, tuberculosis.

^aCompared with students in different classroom from index case.

^bIndex case received TB diagnosis in February 2009.