Table 1.

The mortality rate ratio (MRR) comparing two doses of MV with one dose of MV.

Country and period	Age interval	Comparison (vaccines)	Administration of DTP	Deaths/person-years (pyrs) [N]	MRR two MV vs one MV
RCTs of two doses of MV
Guinea-Bissau 1992–1994 (Benn et al., 1997)	9–18 months	2 MV vs 1 MV	DTP not given with MV; only children with DTP3 before 9-months	0/72.1 pyrs [113] vs 2/70.3 pyrs [107]	0 (0–3.95)a
Guinea-Bissau 2003–2009 (Aaby et al., 2010)	9–18 months	2 MV vs 1 MV	DTP not given with MV; all had DTP3 one month before enrolment	8/713.9 pyrs [1014] vs 39/1370.5 pyrs [1946]	0.39 (0.18–0.83)b
Combined MRR					0.37 (0.17–0.78)
Natural experiment
Guinea-Bissau 1980–1982 (Aaby et al., 1993)	9–60 months	2 MV vs 1 MV	DTP not given in Guinea-Bissau in this period	Not reported in paper	0.41 (0.19–0.75)
General MV campaign
Guinea-Bissau, 2006–2007 (Fisker et al., 2015)	1–4 years, follow-up for 12 months	Had received routine MV and campaign MV vs only routine MV	Effect analysed for those who had received DTP3 before follow-up	16/1372 pyrs [2067] vs 60/2445 pyrs [3074]	0.50 (0.28–0.88)c

^aThe study was restricted to children who had received DTP3 before 9 months. If all children were included the MRR was 0.33 (0.03–3.14).

^bStudy restricted to children who had not received NVAS. If all children were included in the analysis the MRR was 0.61 (0.37–1.01).

^cAdjusted for age, maternal age, maternal education and stratified by village cluster.