A study published Online First (www.thelancet.com) and in an upcoming Lancet shows that 70 children died from H1N1 influenza in the England during the 9 month study period (26 June 2009 to 22 March 2010). Children from England's Bangladeshi and Pakistani communities had much higher mortality than white British children. Children with serious pre-existing disorders—especially chronic neurological diseases (eg, cerebral palsy)—also experienced far higher mortality than previously healthy children. These high-risk groups should be a priority for H1N1 vaccination, concludes the study by Professor Sir Liam Donaldson, former Chief Medical Officer for England and now Chair of the National Patient Safety Agency, UK, and Dr Nabihah Sachedina, former Clinical Advisor to Sir Liam at the UK Department of Health.
Despite national and global reports of the complications of pandemic influenza A H1N1, a detailed analysis of paediatric mortality has not been provided. The authors say: "Following the outset of the pandemic in England in April, 2009, we initiated a confidential investigation into all resulting deaths. This investigation has provided a real-time and comprehensive system of national surveillance, which we have used to examine paediatric deaths in depth. We aimed to provide important evidence to strengthen clinical and public health policies for children during forthcoming influenza seasons and future pandemics."
Deaths during the study period 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. The researchers found that 70 paediatric deaths related to pandemic influenza A H1N1 were reported. They also found:
- The overall childhood mortality rate for H1N1 was 6 per million population. The rate was highest for children aged less than 1 year (14 per million)
- Mortality rates were higher for Bangladeshi children (47 deaths per million population) and Pakistani children (36 deaths per million population) than for white British children (4 deaths per million).
- 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.
- Overall, 45 (64%) children had received oseltamivir (tamiflu): but only seven within 48 h of symptom onset and only three before admission to hospital
- Only two of the children who died had received H1N1 vaccine—too late for it to be effective.
The authors say: "The occurrence of 70 deaths from pandemic influenza A H1N1 in children in 1 year in England is greater than the number of deaths in children every year from leukaemia, and this high childhood mortality was last seen for a single infectious disease (meningococcal disease) in 2001."
Regarding the high ethnic minority mortality rates, the authors say this is consistent with US reports of such minorities suffering more severe illness. They say: "This finding might be attributable to clustering of pandemic influenza A H1N1 cases in areas of England with high ethnic minority populations (such as London and the West Midlands), although other areas with lower ethnic minority populations such as the East Midlands and Yorkshire were also greatly affected. An increased occurrence of pre-existing disorders might exist in ethnic minority children, although no reliable data are available to assess this claim."
The authors note that most children who died presented with typical respiratory symptoms, rather than atypical features that might have identified those at increased risk of a poor outcome.
The authors call for an international pooling of data so that more analysis can be done with higher case numbers, and conclude: "Our findings support the vaccination of children against pandemic influenza A H1N1. Children at greatest risk of severe illness or death should be prioritised. Our data indicate that risk groups include children with pre-existing illness (including chronic neurological or gastrointestinal disease) and those in ethnic minority groups (including Bangladeshi and Pakistani children). However, our findings also suggest that protection cannot be confined to risk groups as 21% of deaths in our cohort occurred in healthy children."
In a linked Comment, Dr Robert A Fowler, Sunnybrook Hospital, University of Toronto, Toronto, Canada, and Dr Philippe Jouvet, St Justine University Hosptial and University of Montreal, Montréal, Canada say: "With the luxury of post-pandemic hindsight and with the findings of Sachedina and Donaldson, we now know that the 2009 H1N1 infection was associated with severe illness and death in greater numbers of children and young adults than previous influenza seasons with other influenza viruses. Any talk of over-reaction to 2009 H1N1 virus might lead to an underappreciation of the very real risks of influenza. The 2009 pandemic was not nearly as severe as feared, but might have been even less so with increased vaccination availability and uptake."
Professor Sir Liam Donaldson, former Chief Medical Officer for England and now of the National Patient Safety Agency, UK. T) +44(0)207 927 9500 E) liam.donaldson@npsa.nhs.uk
Dr Nabihah Sachedina, former Clinical Advisor to Sir Liam at the UK Department of Health. T) +1617 858 0816 E) nabihah@aol.com
Dr Robert A Fowler, Sunnybrook Hospital, University of Toronto, Toronto, Canada. E) rob.fowler@sunnybrook.ca
For full Article and Comment see: http://press.thelancet.com/h1n1children.pdf
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The Lancet