How many episodes of hospital care might be prevented by widespread uptake of pneumococcal conjugate vaccine?

BACKGROUND: It is likely that disease specific infectious morbidity is under-reported. Microbiologically identifiable diseases may be "hidden" in ICD-10 code as "unspecified" disease. AIMS: To estimate the proportion of "unspecified" morbidity of infectious cause in infants and young children reported by Hospital Episode Statistics (HES) in England in 1999 that could reasonably be attributed to Streptococcus pneumoniae, and to calculate what number and proportion of diseases could potentially be prevented by a programme of pneumococcal conjugate vaccination.
METHODS: Proportions of HES "unspecified" septicaemia, meningitis, and pneumonia attributable to pneumococcal infection were estimated by applying theoretical rates obtained from studies using highly sensitive diagnostic tests. The numbers obtained were added to those coded as pneumococcal in origin. The vaccine preventable proportion was then calculated using serogroup coverage, disease specific efficacy, and vaccine uptake.
RESULTS: For infants and children 3 months to 5 years of age in 1999, HES reported 134, 245, and 216 episodes of pneumococcal septicaemia, meningitis, and pneumonia respectively. In addition, 68, 36, and 2548 episodes of "unspecified" disease respectively are probably pneumococcal in origin. For hospitalisations in England in this age group, 157/202 (78%) cases of pneumococcal septicaemia, 218/281 (76%) cases of pneumococcal meningitis, and 452/2764 (16%) cases of pneumococcal pneumonia may be preventable annually by means of pneumococcal conjugate vaccination.
CONCLUSIONS: Paediatric hospital morbidity in England due to pneumococcal septicaemia, meningitis, and pneumonia is under-reported by 34%, 13% and 92% respectively. A larger proportion of morbidity is preventable than implied by ICD-10 code alone.