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Table 3 Vaccination histories in cases and control subjects, unadjusted and adjusted Odds Ratios, and estimates of effectiveness of pneumococcal vaccination against overall invasive pneumococcal disease (IPD) and IPD by vaccine types.

From: Effectiveness of the 23-valent polysaccharide pneumococcal vaccine against invasive pneumococcal disease in people 60 years or older

    Unadjusted analysis Adjusted analysis
Type of infection No. of subjects No. (%) of vaccinated ORa (95% CI) Effectiveness of vaccination % (95% CI) ORb (95% CI) Effectiveness of vaccination % (95% CI)
IPD by vaccine types      (c)  
   Case patients 48 15 (31.3) 0.28 (0.11-0.67) 72% (33-89) 0.23 (0.08-0.60) 77% (40-92)
   Control subjects 96 52 (54.2) p = 0.005   p = 0.003  
Overall IPD      (d)  
   Case patients 88 34 (38.6) 0.34 (0.18-0.63) 66% (37-82) 0.28 (0.15-0.54) 72% (46-85)
   Control subjects 176 104 (59.1) p = 0.001   p < 0.001  
  1. NOTE: OR, odds ratio of vaccination versus no vaccination in cases and controls; Vaccine effectiveness = (1 - matched OR for vaccination)*100%; CI, confidence interval.
  2. aMantel-Haenszel matched Odds Ratio.
  3. bMatched, adjusted Odds Ratio by conditional logistic regression model.
  4. cAdjusted for age, smoking and stroke.
  5. dAdjusted for age, chronic heart disease, alcoholism and smoking.