A new sentinel surveillance system for severe influenza in England shows a shift in age distribution of hospitalised cases in the post-pandemic period

Shelly Bolotin, Richard Pebody, Peter J White, James McMenamin, Luke Perera, Jonathan S Nguyen-Van-Tam, Thomas Barlow, John M Watson, UK Severe Influenza Surveillance System (USISS) Steering Group, J M Watson, R G Pebody, M Catchpole, A Charlett, P White, R Marshall, A Birmingham, S Bolotin, B Taylor, T Barlow, L Perera, J S Nguyen-Van-Tam, J McMenamin, B Smyth, R Salmon, D Thomas, M Rudolf, Shelly Bolotin, Richard Pebody, Peter J White, James McMenamin, Luke Perera, Jonathan S Nguyen-Van-Tam, Thomas Barlow, John M Watson, UK Severe Influenza Surveillance System (USISS) Steering Group, J M Watson, R G Pebody, M Catchpole, A Charlett, P White, R Marshall, A Birmingham, S Bolotin, B Taylor, T Barlow, L Perera, J S Nguyen-Van-Tam, J McMenamin, B Smyth, R Salmon, D Thomas, M Rudolf

Abstract

Background: The World Health Organization and European Centre for Disease Prevention and Control have highlighted the importance of establishing systems to monitor severe influenza. Following the H1N1 (2009) influenza pandemic, a sentinel network of 23 Trusts, the UK Severe Influenza Surveillance System (USISS), was established to monitor hospitalisations due to confirmed seasonal influenza in England. This article presents the results of the first season of operation of USISS in 2010/11.

Methodology/principal findings: A case was defined as a person hospitalised with confirmed influenza of any type. Weekly aggregate numbers of hospitalised influenza cases, broken down by flu type and level of care, were submitted by participating Trusts. Cases in 2010/11 were compared to cases during the 2009 pandemic in hospitals with available surveillance data for both time periods (n = 19). An unexpected resurgence in seasonal A/H1N1 (2009) influenza activity in England was observed in December 2010 with reports of severe disease. Reported cases over the period of 4 October 2010 to 13 February 2011 were mostly due to influenza A/H1N1 (2009). One thousand and seventy-one cases of influenza A/H1N1 (2009) occurred over this period compared to 409 at the same Trusts over the 2009/10 pandemic period (1 April 2009 to 6 January 2010). Median age of influenza A/H1N1 (2009) cases in 2010/11 was 35 years, compared with 20 years during the pandemic (p = <0.0001).

Conclusions/significance: The Health Protection Agency successfully established a sentinel surveillance system for severe influenza in 2010/11, detecting a rise in influenza cases mirroring other surveillance indicators. The data indicate an upward shift in the age-distribution of influenza A/H1N1 (2009) during the 2010/11 influenza season as compared to the 2009/10 pandemic. Systems to enable the ongoing surveillance of severe influenza will be a key component in understanding and responding to the evolving epidemiology of influenza in the post-pandemic era.

Conflict of interest statement

Competing Interests: JSN-V-T has received funding to attend influenza related meetings, lecture and consultancy fees (ceasing in September 2010), and research funding from several influenza antiviral drug and vaccine manufacturers, and is a former employee of SmithKline Beecham plc. (now GlaxoSmithKline), Roche Products Ltd, and Aventis-Pasteur MSD (now Sanofi-Pasteur MSD). PJW has received funds from Kendle Healthcare for an expert opinion on influenza and has received funding from Elsevier in 2010 to attend an influenza-related meeting. No other relationships, activities, or nonfinancial competing interests exist that could appear to have influenced the submitted work. This does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials.

Figures

Figure 1. Number of hospitalised cases of…
Figure 1. Number of hospitalised cases of influenza by type and by week of admission with weekly Royal College of General Practitioners (RCGP) influenza-like illness (ILI) consultation rate per 100 000 population: week 40 2010–week 6 2011, USISS sentinel network (n = 23), England.
Figure 2. Number of hospitalised cases by…
Figure 2. Number of hospitalised cases by age group and by week of admission: week 40 2010–week 6 2011, USISS sentinel network (n = 23), England.

References

    1. World Health Organisation. Regional Office for Europe Guidance for Influenza Surveillance in Humans. 2009. Geneva.
    1. European Centre for Disease Prevention and Control. Overview of surveillance of influenza 2009/2010 in the EU/EEA. 2009. Stockholm.
    1. RCGP Research and Surveillance Centre Weekly Returns Service. Communicable and Respiratory Disease Report for England and Wales, week 49 2010. 2010. Birmingham.
    1. Campbell CN, Mytton OT, McLean EM, Rutter PD, Pebody RG, et al. Hospitalization in two waves of pandemic influenza A(H1N1) in England. Epidemiol Infect Nov. 2010;26:1–10.
    1. Office for National Statistics website,, Population Estimates for UK, England and Wales, Scotland and Northern Ireland, mid 2009. Available: . Accessed 2011 Dec 20.
    1. Rothman KJ. Modern epidemiology. Boston: Little, Brown; 1986.
    1. Health Protection Agency: Weekly Report of the Laboratory Surveillance System (DataMart) for Influenza and Other Major Respiratory Viruses in England. 20 April 2000–4 January 2010 and 4 October 2010–17 January 2011. 2011. London.
    1. Health Protection Agency: Weekly National Influenza Report; Summary of UK surveillance of influenza and other seasonal respiratory illnesses. Week 52. 2010. London.
    1. Health Protection Agency: Weekly National Influenza Report; Summary of UK surveillance of influenza and other seasonal respiratory illnesses. Week 51. 2010. London.
    1. Department of Health: Winterwatch; Winter Health Data. 6 January. 2011. London.
    1. Hardelid P, Andrews NJ, Hoschler K, Stanford E, Baguelin M, et al. Assessment of baseline age-specific antibody prevalence and incidence of infection to novel influenza A/H1N1 2009. Health Technol Assess. 2010;14(55):115–192.
    1. Ellis J, Galiano M, Pebody R, Lackenby A, Thompson C, et al. Virological analysis of fatal influenza cases in the United Kingdom during the early wave of influenza in winter 2010/11. Euro Surveill Jan 6. 2011;16(1):Article 1. Available: . Accessed: 2011 Dec 31.
    1. Presanis AM, Pebody RG, Paterson BJ, Tom BD, Birrell PJ, et al. Changes in severity of 2009 pandemic A/H1N1 influenza in England: a Bayesian evidence synthesis. BMJ. 2011;Sept 8;343:d5408. doi: .
    1. Zakikhany K, Degail MA, Lamagni T, Waight P, Guy R, et al. Increase in invasive Streptococcus pyogenes and Streptococcus pneumoniae infections in England, December 2010 to January 2011. Euro Surveill. 2011;Feb 3;16(5):pii = 19785. Available: . Accessed: 2011 Dec 31.
    1. Athanasiou M, Baka A, Andreopoulou A, Spala G, Karageorgou K, et al. Influenza surveillance during the post-pandemic influenza 2010/11 season in Greece, 04 October 2010 to 22 May 2011. Euro Surveill. 2011;Nov;16(44):pii-20004. Available: . Accessed: 2011 Dec 31.
    1. Health Protection Surveillance Centre: Influenza Surveillance in Ireland Weekly Report (2011) Week 2 (10th–16th January 2011)
    1. Bansal S, Pourbohloul B, Hupert N, Grenfell B, Ancel Meyers L. The shifting demographic landscape of pandemic. PLoS One. 2010;5:2.
    1. Gilbert V, Caraway C, Bruce J, Mogabgab W. Epidemic recurrence of asian influenza in lousiana, 1959–1960. Am J Public Health. 1962;52:1432–43.

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