A cluster randomised controlled trial of two rounds of mass drug administration in Zanzibar, a malaria pre-elimination setting—high coverage and safety, but no significant impact on transmission

Table 3 Cumulative malaria case incidence at 3, 6, 12, and 16 months after MDA

	Malaria cases		Cumulative incidence (cases/1000 population; range between shehias)
Time period	Intervention (N = 10,944)	Control (N = 12,307)	Intervention	Control	p value
Baseline
6 months (May–Nov 2015)	128	126	11.7; 7.7–16.1	10.2; 6.4–32.8	0.130
12 months (May 2015–April 2016)	150	146	13.7; 9.8–19.6	11.9; 7.5–36.8	0.105
Post-MDA
3 months (May–Aug 2016)	31	41	2.8; 0.0–10.3	3.3; 0.9–8.0	0.721
6 months (May–Nov 2016)¹	43	52	3.9; 0.0–13.1	4.2; 2.1–8.0	0.442
12 months (May 2016–April 2017)	58	71	5.3; 0.0–13.1	5.8; 3.1–10.4	0.382
16 months (May 2016–Aug 2017)	143	208	13.1; 5.4–28.0	16.9; 6.7–31.8	0.130
Post-MDA cases without travel history
3 months (May–Aug 2016)	18	23	1.6; 0.0–9.3	1.9; 0.0–8.0	0.716
6 months (May–Nov 2016)	22	29	2.0; 0.0–11.2	2.4; 0.9–8.0	0.277
12 months (May 2016–April 2017)	31	41	2.8; 0.0–11.2	3.3; 1.1–8.0	0.315
16 months (May 2016–Aug 2017)	109	160	10.0; 5.4–26.1	13.0; 2.7–30.8	0.279