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Table 2 Main outcomes of randomized trials of pneumococcal vaccines

From: Are the pneumococcal polysaccharide vaccines effective? Meta-analysis of the prospective trials

Outcome Patient group Number of trials Number of patients Percent affected without vaccine Percent affected with vaccine Relative risk (95%CI) Number-needed-to-treat (95%CI)
All pneumonias Healthy immunocompetent 3 14 567 6.5 3.1 0.56 (0.47 to 0.66) 29 (24 to 36)
  Elderly or high risk 5 7 837 6.8 7 1.08 (0.92 to 1.27)  
Pneumococcal pneumonias Healthy immunocompetent 3 14 567 3.1 0.5 0.16 (0.11 to 0.23) 38 (33 to 45)
  Elderly or high risk 7 22 479 1.9 1.7 0.88 (0.72 to 1.07)  
Lower respiratory tract infection Healthy immunocompetent 2 10 067 5.6 4.1 0.85 (0.71 to 1.02)  
  Elderly or high risk 3 17 195 9.4 9.9 1.06 (0.97 to 1.16)  
Pneumonia-related death Healthy immunocompetent 1 11 958 1.6 1.1 0.70 (0.50 to 0.96) 213 (114 to 1660)
  Elderly or high risk 8 22 559 1.1 1 0.93 (0.72 to 1.20)  
Pneumococcal bacteraemia Healthy immunocompetent 1 5 427 3.8 0.7 0.18 (0.09 to 0.34) 32 (26 to 44)
  Elderly or high risk 3 927 1.4 0.8 0.53 (0.14 to 1.94)  
  1. Note: Details of patient groups are given in the textNumbers-needed-to-treat are only given where there is a statistical benefit of treatment over control.