Efficacy of pneumococcal polysaccharide vaccine/The commentators respond

• Published in: Canadian Medical Association journal (CMAJ) 2009-05, Vol.180 (11), p.1134
• Main Authors: Scott, Pippa, Huss, Anke, Stuck, Andreas E, Trotter, Caroline, Egger, Matthias, Andrews, Ross M, Moberley, Sarah A
• Format: Article
• Language: English
• Subjects: Systematic review
• ISSN: 0820-3946; 1488-2329

Pneumococcal infections cause a large burden of disease worldwide, and control of this disease with an efficacious vaccine would be highly desirable. However, we do not think that the pneumococcal polysaccharide vaccine is the answer. After over 60 years of research on the pneumococcal polysaccharide vaccine, we might expect there to be convincing evidence of efficacy if the vaccine offered worthwhile protection. We do not recommend conducting further studies on this vaccine, as [Ross M. Andrews PhD MPH] and [Sarah A. Moberley BN MPH] suggest, but rather suggest exploring alternative possibilities to pneumococcal polysaccharide vaccine. Currently, the conjugate vaccine seems to be the most promising candidate, but it needs to be thoroughly evaluated. Prevention of invasive pneumococcal disease is the primary purpose of vaccination programs with polysaccharide pneumococcal vaccine in adults. We contended that the World Health Organization had considered the findings of the meta-analysis by [Anke Huss PhD] and colleagues in its recent position paper on the use of pneumococcal vaccine in adults but that its recommendations had remained "virtually unchanged."6 We accept the points of clarification by Huss and colleagues on the subtle wording changes they identified, but by our reading the World Health Organization falls well short of calling for cessation of existing polysaccharide pneumococcal vaccine programs for adults in its recent position paper. In their letter, Huss and colleagues appear to have moved away from this suggestion, which we think is appropriate given the evidence provided in their review. Rather than demonstrating a lack of convincing evidence of efficacy after 60 years of research on the polysaccharide pneumococcal vaccine, we think the study by Huss and colleagues further highlights the limitations of the available clinical trial data when assessing the vaccine's impact against rare events like invasive pneumococcal disease. The most recent and best quality clinical trials, as determined by Huss and colleagues, were conducted largely among populations with chronic illness or severe immunosuppression or both. In these trials there were very few cases of invasive pneumococcal disease: 7 cases of definitive pneumococcal pneumonia from 2 studies and 44 cases of bacteremia from 6 studies (most of which were among HIV-infected adults in Uganda).