Fast track — ArticlesEfficacy of nine-valent pneumococcal conjugate vaccine against pneumonia and invasive pneumococcal disease in The Gambia: randomised, double-blind, placebo-controlled trial
Introduction
Pneumonia causes an estimated 19% of the 10 million childhood deaths worldwide.1 Up to half of all cases of severe childhood pneumonia are caused by pneumococcus in developing countries.2 In The Gambia3 and other African countries,4, 5 invasive pneumococcal disease rates are up to tenfold higher than in industrialised countries, and the disease is a major cause of admissions and deaths.5 The high burden of pneumococcal disease in The Gambia prompted studies to assess pneumococcal vaccines. Conjugate vaccines were shown to be safe, immunogenic, and induce immunological memory in Gambian infants.6, 7, 8 In view of these findings, we aimed to assess the efficacy of a nine-valent pneumococcal conjugate vaccine against radiological pneumonia in rural areas of The Gambia.
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Study setting
We undertook a randomised, double-blind, placebo-controlled trial in the Upper River Division and Central River Division of The Gambia, covering an area of 5000 km2. The estimated population of this area was 380 000 in 2000.9
The prevalence of HIV-1 infection among antenatal clinic attendees in this region has remained stable at about 1% since 1993.10 In background studies from 1989–93, the mortality rate in infants was 80 per 1000 child-years, and in children age 1–4 years it was 19 per 1000
Results
We recruited children from August, 2000, to February, 2003. Vaccination ended in April, 2003, and clinical follow-up ended in April, 2004. 22 170 children were screened for eligibility, of whom 17 437 (79%) participated in the study (figure). Table 1 shows characteristics of children in the per-protocol analysis. Median age at receipt of the first dose of vaccine or placebo was 11 weeks (IQR 8–16) and for the third dose it was 24 weeks (19–32). Median length of follow-up was 103 weeks (84–116)
Discussion
We have shown that pneumococcal conjugate vaccine has high efficacy against radiological pneumonia and substantially reduces admissions and improves child survival. Similar to findings from the USA19, 20 and South Africa,21 we found that conjugate pneumococcal vaccine is efficacious against invasive pneumococcal disease. We have confirmed and defined more precisely vaccine efficacy against pneumonia with consolidation, and shown that the preventable burden of pneumococcal-related pneumonia is
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