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Table 4 Vaccination effectiveness in those age 65 years and over (excluding very high risk) with equivalent number needed to vaccinate (NNV) estimates

From: The impact and effectiveness of pneumococcal vaccination in Scotland for those aged 65 and over during winter 2003/2004

Group Number of vaccinated cases Total number of cases % Vaccination Effectiveness (95% CI) Equivalent Number Needed to Vaccinate #(NNV) with 95% CI
Age 65+ years     
   All     
Crude 57 135 64.2 (49.6, 74.5) -
Adjust    61.7 (45.1, 73.2) 5206 (4388, 7122)
(Age/Sex) 30 59 53.5 (22.5, 72.1) 6059 (4499, 14407)
   Male 27 76 71.1 (53.7, 81.9) 9835 (3987, 5944)
   Female     
Age 65–74 years     
   All 23 49 54.4 (20.1, 74.0) 9724 (7148, 26317)
   Male 13 24 41.0 (-31.7, 73.6) (10726) §
   Female 10 25 64.6 (21.1, 84.1) 9835 (7554, 30110)
Age 75+ years     
   All 34 86 68.8 (52.0, 79.8) 3145 (2712, 4162)
   Male 17 35 60.5 (23.3, 79.6) 3801 (2895, 9891)
   Female 17 51 73.9 (53.3, 85.4) 2836 (2454, 3932)
  1. * Vaccination effectiveness as determined by the screening method (see Methods)
  2. # NNV: number needed to vaccinate to prevent one case (calculated as 1/attributable risk; based on equivalent annual incidence of IPD in 2003/2004.
  3. §Hypothetical value for NNV given non-significant test result