Table 4 Reports from The Gambia of infant HBV vaccination efficacy against chronic HBV infection (HBsAg+) at various ages in childhood

Age (years)

Vaccinees

Controls

% vaccine efficacy (and 95% CI)

Nationwide GHIS cohort, born 1986–90 and surveyed periodically in 1990–2008, vs concurrently born controls

~4

4/720 (0.6)

78/816 ( 9.6)

94% (84–98)

~9

4/675 (0.6)

85/823 (10.3)

95% (84–98)

~15

2/492 (0.4)

51/420 (13.2)

97% (92–99)

~20*

2/255 (0.8)

59/475 (12.4)

94% (76–99)

All ages

12/2142 (0.6)

273/2534 (10.8)

95% (mean)

Keneba village, born 1984–2002 and surveyed in 2003, vs historical controls surveyed in 1984

1-4

0/176 (0.0)

24/236 (10.2)

5–9

2/203 (1.0)

32/205 (15.6)

10–14

0/185 (0.0)

19/135 (14.1)

15+

3/224 (1.3)

8/47 (17.0)

All ages

5/788 (0.6)

83/623 (13.3)

94% mean**