Further prospective randomised controlled trial is necessary

Editor—Paula McDonald and colleagues have shown that a pneumococcal campaign based in general practice is feasible and offers the potential to increase substantially the proportion of patients at risk of pneumococcal infections who are vaccinated.1 Unfortunately, there remains a lack of robust evidence, particularly outcome data, to support pneumococcal vaccination in all the at risk groups identified in their paper. For example, one of the studies quoted by McDonald and colleagues fails to show any evidence of a protective effect of vaccination in patients with alcohol dependence or cirrhosis, sickle cell disease, chronic renal failure, or Hodgkin's disease.2 These conditions, however, are included in most lists of target groups for pneumococcal vaccination, including McDonald and colleagues'.

Butler et al's work also shows that the vaccine's efficacy in the conditions with a higher prevalence, such as congestive cardiac failure, may be as low as 17% or as high as 88% when confidence intervals are considered.2 Small sample sizes make conclusions difficult to draw.

Other work has relied on the development of pneumococcal antibodies rather than reductions in morbidity and mortality. We have collated details of 40 trials and 15 other papers on this topic. The general trends show that the groups at greatest risk from pneumococcal infection are those with the most impaired immune response. This potentially limits the usefulness of pneumococcal vaccination programmes.

Fine et al have published a meta-analysis of randomised controlled trials of pneumococcal vaccination, which McDonald and colleagues did not cite.3 They concluded that “evidence from randomized controlled trials fails to demonstrate vaccine efficacy for pneumococcal infection-related or other medical outcomes in the heterogeneous group of subjects currently labelled as high risk.”

A protocol for a systematic review of the literature in relation to pneumococcal vaccination has been posted in the Cochrane Database …