Preterm Children Have Higher Risk Than Full-term Children of Invasive Pneumococcal Disease During the First 2 Years of Life.

BACKGROUND

A few previous studies have reported an increased risk of invasive pneumococcal disease (IPD) in children born preterm, but this has not been investigated in a cohort study. The impact of 7-valent pneumococcal conjugate vaccine (PCV7) on IPD incidence rates in preterm children is unknown.

METHODS

Data from the Medical Birth Registry of Norway (2002-2010) were linked to other national registries. In total, 628,138 children were included in our study and followed until 2 years of age. Incidence rate ratios (IRRs) and confidence intervals (CIs) were estimated with Poisson regression.

RESULTS

We identified 411 cases of IPD. We observed higher rates of IPD in preterm than in full-term children for the intervals 0-23, 0-5 and 6-23 months of age, IRRs = 1.83 (95 % CI: 1.36-2.47), 2.95 (95% CI: 1.44-6.06) and 1.69 (95% CI: 1.22-2.34), respectively. The risk for IPD was reduced in the PCV7-period (2007-2010) compared with that of the pre PCV7-period (2002-2005) for children 6-23 months of age, IRRs = 0.20 (95% CI: 0.08-0.53) for preterm children and 0.28 (95% CI: 0.21-0.38) for full-term children, but not for those 0-5 months of age, IRRs = 1.94 (95% CI: 0.48-7.80) and 0.71 (95% CI: 0.38-1.33).

CONCLUSIONS

Preterm children had an increased risk of IPD. After introduction of PCV7, the rate of IPD was reduced among preterm and full-term children from 6 months of age.