Background
Pneumonia remains the leading cause of death in young children. The poor specificity of chest radiographs
(CXRs) to diagnose
pneumococcal pneumonia may underestimate the efficacy of pneumococcal conjugate vaccine in preventing pneumococcal pneumonia.
Methods and Findings
The efficacy of nine-valent pneumococcal conjugate vaccine among children not infected with HIV (21; 95 confidence interval, 137) increased when CXR-confirmed pneumonia was associated with serum C-reactive protein of 120 mg/l (12mg/dl) or more and
procalcitonin of 5.0 ng/ml or more (64; 95 confidence interval, 2383). Similar results were observed in children infected with HIV.
Conclusion
C-reactive protein and procalcitonin improve the specificity of CXR to diagnose pneumococcal pneumonia and may be useful for the future evaluation of the effectiveness of pneumococcal conjugate vaccine in preventing pneumococcal pneumonia.