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Research

Mortality from pandemic A/H1N1 2009 influenza in England: public health surveillance study

BMJ 2009; 339 doi: http://dx.doi.org/10.1136/bmj.b5213 (Published 10 December 2009) Cite this as: BMJ 2009;339:b5213
  1. Liam J Donaldson, chief medical officer for England1,
  2. Paul D Rutter, clinical adviser1,
  3. Benjamin M Ellis, clinical adviser1,
  4. Felix E C Greaves, clinical adviser1,
  5. Oliver T Mytton, clinical adviser1,
  6. Richard G Pebody, consultant medical epidemiologist2,
  7. Iain E Yardley, clinical adviser1
  1. 1Department of Health, Richmond House, London SW1A 2NS
  2. 2Health Protection Agency, Colindale, London
  1. Correspondence to: L Donaldson liam.donaldson{at}dh.gsi.gov.uk
  • Accepted 30 November 2009

Abstract

Objective To establish mortality from pandemic A/H1N1 2009 influenza up to 8 November 2009.

Design Investigation of all reported deaths related to pandemic A/H1N1 in England.

Setting Mandatory reporting systems established in acute hospitals and primary care.

Participants Physicians responsible for the patient.

Main outcome measures Numbers of deaths from influenza combined with mid-range estimates of numbers of cases of influenza to calculate age specific case fatality rates. Underlying conditions, time course of illness, and antiviral treatment.

Results With the official mid-range estimate for incidence of pandemic A/H1N1, the overall estimated case fatality rate was 26 (range 11-66) per 100 000. It was lowest for children aged 5-14 (11 (range 3-36) per 100 000) and highest for those aged ≥65 (980 (range 300-3200) per 100 000). In the 138 people in whom the confirmed cause of death was pandemic A/H1N1, the median age was 39 (interquartile range 17-57). Two thirds of patients who died (92, 67%) would now be eligible for the first phase of vaccination in England. Fifty (36%) had no, or only mild, pre-existing illness. Most patients (108, 78%) had been prescribed antiviral drugs, but of these, 82 (76%) did not receive them within the first 48 hours of illness.

Conclusions Viewed statistically, mortality in this pandemic compares favourably with 20th century influenza pandemics. A lower population impact than previous pandemics, however, is not a justification for public health inaction. Our data support the priority vaccination of high risk groups. We observed delayed antiviral use in most fatal cases, which suggests an opportunity to reduce deaths by making timely antiviral treatment available, although the lack of a control group limits the ability to extrapolate from this observation. Given that a substantial minority of deaths occur in previously healthy people, there is a case for extending the vaccination programme and for continuing to make early antiviral treatment widely available.

Footnotes

  • We are grateful to the many clinicians in England who supplied the clinical information on their patients, Brian Healy (Harvard School of Public Health) for statistical advice, Gillian Perkins, Tara Fajeyisan, and Emma Stanton for managing the database, Mobasher Butt and David O’Reilly for their work establishing the project, and Andre Charlett of the Health Protection Agency for providing estimated case numbers.

  • Contributors: LJD conceived the project in conjunction with his clinical advisers and has overseen the work and drafting of the manuscript. PDR, BME, FECG, IEY, and OTM all had a role in designing the data collection process, collecting the data, analysing the data, and drafting the manuscript. RGP advised on analysis and critiqued the manuscript. LJD is guarantor.

  • Funding: This work was conducted as part of the public health response to pandemic influenza in England. No additional funding was sought.

  • Competing interests: LJD is the chief medical officer for England. In this role he advises the government on public health policy, including the management of the pandemic. PDR, BME, FECG, IEY, and OTM support him in this task. All authors have completed the unified competing interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) (URL) and declare (1) no financial support for the submitted work from anyone other than their  employer; (2) no financial relationships with commercial entities that might have an interest in the submitted work; (3) no spouses, partners, or children with relationships with commercial entities that might have an interest in the submitted work; and (4) no non-financial interests that may be relevant to the submitted work.

  • Ethical approval: This exercise was undertaken as part of a public health surveillance programme for the pandemic. As such no explicit ethical approval was necessary or sought. This exercise was undertaken under the Health Service (Control of Patient Information) Regulations SI1438/2002, which provide a basis for collecting and processing data without patient consent for the purposes of communicable disease control in England.

  • Data sharing: No additional data available.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/2.0/ and http://creativecommons.org/licenses/by-nc/2.0/legalcode.

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