Abstract

Background: The annual reported incidence rates for laboratory confirmed invasive pneumococcal disease (IPD) underestimate the true burden of invasive disease attributable to pneumococcal infection.

Aims: To estimate the proportion of “unspecified” mortality of infectious cause in infants and young children aged 1 month to 4 years reported by the Office for National Statistics (ONS) in England and Wales that could reasonably be attributed to IPD, thereby revising the total number of deaths per year potentially attributable to IPD, and producing a more accurate figure for the number of deaths that may be prevented by a programme of pneumococcal conjugate vaccination.

Methods: Polymerase chain reaction, latex agglutination, and other alternate methodologies to microbiological culture have been applied in various studies to the detection of Streptococcus pneumoniae. Some of these tests have been shown to be more sensitive indicators of pneumococcal infection. In our analysis the implications of these tests were applied theoretically to the “unspecified” clinical deaths caused by septicaemia, meningitis, and pneumonia reported by the ONS, with a 20% correction/reduction factor for nasopharyngeal carriage which these sensitive tests may coincidentally detect.

Results: The ONS reported an average of 13 deaths per year (1989–99) in infants and children aged 1 month to 4 years caused by pneumococcal septicaemia, meningitis, or pneumonia. By applying the rates for the more sensitive tests to the most recent ONS “unspecified” mortality data available (1999), the actual annual number of deaths caused by IPD in the age group 1 month to 4 years is shown to be at least as high as 43.

Conclusions: The mortality as a result of IPD in infants and young children may be at least three times the reported rate. The 7 valent pneumococcal conjugate vaccine may have the potential to prevent up to 26 (61%) of the IPD deaths per year in infants and young children in England and Wales alone.