Table 3.

Number of smallpox vaccination scars and subsequent mortality.

Study (reference)	Comparison (deaths/persons)	Adjusted mortality rate ratio (MRR, 95% CI)	MRR (95% CI) by number of scars	Testing trend by number of scars
Bissau city (Aaby et al., 2006), Guinea-Bissau (1998–2002), N = 1893 aged 25 + years	Vaccinia scar (75/1187) vs no scar (60/500)	0.60 (0.41–0.87) F: 0.51 (0.30–0.84) M: 0.72 (0.42–1.24)	1 scar: 0.65 (0.40–0.91) 2 scars: 0.54 (0.29–0.97) 3 + scars: 0.44 (0.13–1.46)	Trend for decreasing MRR with number of scars: MRR = 0.73 (95% 0.56–0.95)
Rural area (Jensen et al., 2006), Guinea-Bissau (2003–2006), N = 367	Vaccinia scar (29/251) vs no scar (9/35)	0.22 (0.08–0.61) F: 0.19 (0.06–0.57) M:0.40 (0.04–3.74)	1 scar: 0.24 (0.09–0.68) 2 + scars: 0.14 (0.03–0.56)