Table 3

 Numbers of pneumonia patients (first episode) in a prospective randomised trial showing efficacy of 23-serotype pneumococcal vaccine

Intervention groupNon-intervention groupVaccine efficacy*p value†NNT
nNnN%95% CIn95% CI
CAP-PN, community acquired pneumonia of unknown aetiology and pneumococcal pneumonia; FEV1, forced expiratory volume in 1 second; NNT, number needed to treat.
*Vaccine efficacy  =  1 − RR × 100.
†The p value for pneumococcal pneumonia is 0.06 using the Fisher’s exact test (two sided) and 0.03 (single sided). This last p value is very similar to that obtained with the log rank test (p = 0.025, Kaplan-Meier curves).
CAP-PN
    All patients252983329824(−24 to 54)0.333
    <65 years3911611676(20 to 93)0.01310(6 to 31)
    ⩾65 years2220717182−14(−107 to 38)0.801
FEV1 <40%121322011448(−7 to 80)0.076
FEV1 ⩾40%1316613184−11(−132 to 47)0.945
Age <65 years and FEV1 <40%146104091(35 to 99)0.0023(2 to 4)
Pneumococcal pneumonia029852980.061