Paediatric mortality related to pandemic influenza A H1N1 infection in England: an observational population-based study

Abstract

Background: Young people (aged 0-18 years) have been disproportionately affected by pandemic influenza A H1N1 infection. We aimed to analyse paediatric mortality to inform clinical and public health policies for future influenza seasons and pandemics.

Methods: All paediatric deaths related to pandemic influenza A H1N1 infection from June 26, 2009, to March 22, 2010 in England were identified through daily reporting systems and cross-checking of records and were validated by confirmation of influenza infection by laboratory results or death certificates. Clinicians responsible for each individual child provided detailed information about past medical history, presentation, and clinical course of the acute illness. Case estimates of influenza A H1N1 were obtained from the Health Protection Agency. The primary outcome measures were population mortality rates and case-fatality rates.

Findings: 70 paediatric deaths related to pandemic influenza A H1N1 were reported. Childhood mortality rate was 6 per million population. The rate was highest for children aged less than 1 year. Mortality rates were higher for Bangladeshi children (47 deaths per million population [95% CI 17-103]) and Pakistani children (36 deaths per million population [18-64]) than for white British children (4 deaths per million [3-6]). 15 (21%) children who died were previously healthy; 45 (64%) had severe pre-existing disorders. The highest age-standardised mortality rate for a pre-existing disorder was for chronic neurological disease (1536 per million population). 19 (27%) deaths occurred before inpatient admission. Children in this subgroup were significantly more likely to have been healthy or had only mild pre-existing disorders than those who died after admission (p=0·0109). Overall, 45 (64%) children had received oseltamivir: seven within 48 h of symptom onset.

Interpretation: Vaccination priority should be for children at increased risk of severe illness or death from influenza. This group might include those with specified pre-existing disorders and those in some ethnic minority groups. Early pre-hospital supportive and therapeutic care is also important.

Funding: Department of Health, UK.