The contribution of the case-control approach to vaccine evaluation: Pneumococcal and Haemophilus influenzae type B PRP vaccines.
Case-control studies have had an increasing role in the postlicensure evaluation of vaccine efficacy. We review the contribution of case-control studies to the evaluation of vaccines for Streptococcus pneumoniae (pneumococcus) and Haemophilus influenzae type b (Hib) and compare these studies with clinical trials of these vaccines. We located one clinical trial and eight case-control studies of Hib PRP vaccine efficacy and three clinical trials and four case-control studies of pneumococcal vaccine efficacy. The pooled estimate of Hib PRP vaccine efficacy based on the case-control studies (0.38, 95% CL = 0.15-0.55) was lower than the efficacy of the clinical trial conducted in Finland (0.8, 95% CL = 0.57-0.98). The pooled estimate of pneumococcal vaccine efficacy based on the case-control studies (0.56, 95% CL = 0.44-0.66) was also lower than the pooled efficacy of the South African clinical trials (0.79, 95% CL = 0.69-0.86). Although the clinical trials provided crucial evidence that these vaccines worked in selected international settings, the direct evidence of efficacy in the United States rests largely on the case-control results. The utility of the case-control approach is supported.
Mills
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Department of Family Medicine, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Brunswick 08903-0019, USA.
Rhoads
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D000293:Adolescent; D000328:Adult; D016667:Bacterial Capsules; D001428:Bacterial Vaccines / Q000008:administration & dosage*; D016022:Case-Control Studies; D002423:Cause of Death; D002648:Child; D002675:Child, Preschool; D005260:Female; D006192:Haemophilus Infections / Q000401:mortality / Q000517:prevention & control; D018073:Haemophilus Vaccines / Q000008:administration & dosage*; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D022242:Pneumococcal Vaccines; D011018:Pneumonia, Pneumococcal / Q000401:mortality / Q000517:prevention & control; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage*; D011358:Product Surveillance, Postmarketing; D012372:ROC Curve; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome
D001428:Bacterial Vaccines; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D022242:Pneumococcal Vaccines; D011135:Polysaccharides, Bacterial