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Eurosurveillance, Volume 12, Issue 44, 01 November 2007
Articles

Citation style for this article: Nicoll A, Influenza team (ECDC). Public Health Measures in an Influenza Pandemic – the importance of surveillance. Euro Surveill. 2007;12(44):pii=3300. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=3300

Public Health Measures in an Influenza Pandemic – the importance of surveillance

A Nicoll on behalf of the Influenza Project Team (influenza@ecdc.europa.eu)*, European Centre for Disease Prevention and Control, Stockholm, Sweden

*B Ciancio, K Fernandez de la Hoz, P Kreidl, H Needham, A Nicoll, C Varela, P Vasconcelos, J Todd Webber and A Wurz

One of the most controversial aspects of planning for a pandemic concerns the role and application of public health measures that could reduce its impact. There are many measures it is proposed could be taken (Table 1) with the aim of achieving a reduction of the peak levels of transmission in a pandemic in the European Union and push back the bulk of transmission towards the natural decline that occurs in the warmer summer months, and when specific pandemic vaccines start becoming available.

Various opinions have been expressed concerning the measures, with perhaps the fiercest debate taking place in the United States. Some have argued that combinations of measures could save many lives and perhaps even contain a pandemic when it reaches a new country [1,2]. Others consider that most measures will be more trouble than they are worth [3]. This range of opinion stems from two facts. Firstly, the effectiveness of most of the measures in reducing transmission is unknown; and secondly, almost all of them (with the exception of hand-washing and personal respiratory hygiene) come with costs and substantial secondary consequences [3,4,5]. These could include adverse events following from the measures themselves, for example closing schools and pre-school care might lead to parents being lost to the work-force because they have to take time off work to care for their children. The World Health Organization (WHO) has had a table of evidence-based positions since 2005 on many of the less controversial measures (none are uncontroversial) [6-8]. However, a table alone cannot deal with the more difficult and expensive social distancing measures (e.g. school closures, mass gatherings, internal travel restrictions) and the WHO document does not cover the pharmaceutical measures (antivirals and human H5N1 vaccines) that have emerged since its publication [5,6].

In Europe, it is unlikely that 'one size will fit all' except for the few measures that are at the ' relatively easy' (hand-washing and personal respiratory hygiene) or ' very difficult – don’t do it' (border closure) extremes. For example, consider Measure 14 – closing schools in a locality as a pandemic approaches – which is sometimes proposed on the grounds that children in the 1957 pandemic were considered to have been responsible for a disproportionate amount of viral transmission, and so keeping them apart could reduce the impact [1,2,9]. Closure of a central secondary school might make sense in a low population density rural area where the school is an important infection dissemination point and children from scattered communities come together. Equally, however, school closures may be ineffective or even counterproductive in dense urban areas, where children denied school would have to be cared for either by still mixing out of school in group care or requiring their parents to leave work to care for them.

Even if simple solutions were possible, it is not in the mandate of the European Centre for Disease Prevention and Control (ECDC) to prescribe measures or determine policy. Rather, its job is to produce the scientific evidence that can inform decisions [10]. Hence to inform discussions and potential decisions by member states and EU bodies, the ECDC recently published an interim Guide to Public Health Measures to Reduce the Impact of Influenza Pandemics during Phase 6 - 'The ECDC Menu' [11]. The aim of the document is to build on the WHO position and present all the measures that EU Member States and institutions individually or collectively could consider to reduce the impact of an influenza pandemic (Table 1). It does not make recommendations on what EU Member States should do, or EU bodies recommend. Rather the 'Menu' summarises the current status of public health and scientific information on what is known or can be said about the likely effectiveness, costs (direct and indirect), acceptability, public expectations and other practical considerations of the individual measures. The primary intended audience is those who develop policy and decision-makers, although secondary audiences are all those concerned with influenza, the public and the media.

The understanding by the latter groups of the measures and their limitations will be crucial to their successful application in a pandemic. It should be stressed that the document only applies to measures that would be taken during Phase 6 of a pandemic, i.e. when global transmission is underway, although it should also prove useful during bad epidemics of seasonal influenza (which from previous experience should be expected after the next pandemic). It does not address the somewhat different circumstances of Phases 4 and 5 of a pandemic, nor the unique needs of the first emergence of a putative pandemic strain (when the WHO Rapid Containment Strategy would apply [12]). Neither does the document address the complex planning and policy issues that arise over how to sustain key services in a pandemic.

Surveillance in a pandemic – the ECDC’s working paper
Closely related to the issue of the public health measures is the virological and epidemiological information that will need to be gathered rapidly in a pandemic, so-called Surveillance in a Pandemic (Table 2).

This activity will be crucial because pandemics are so variable but their characteristics to a large extent determine the control measures [1,2]. From all historical experience, we know that another pandemic is inevitable – but little else can be predicted about it. We do not when it will come, its viral type (although H2, H5, H7 and H9 are considered the more likely types) the severity, the groups among whom transmission will be highest and whether countermeasures like antivirals, that work on seasonal flu are effective for the pandemic strain. [13,14], Countries that are investing in human avian influenza vaccines will want to know if they are working and without side effect [15]. This is vital information. The strain type and strain isolation will lead to tests and the specific pandemic vaccine. If the virus has high virulence (say a Case Fatality Rate (CFR) over 0.5%) a number of European national plans suggest more drastic public health measures should be considered [16,17]. The United States has gone further developing a five point grading scale based on CFR and akin to that used for hurricanes in the US, and so well known to the American public [9].

Getting hold of the pandemic virus strain quickly may be difficult in a pandemic. Gathering accurate epidemiologic data in a pandemic will be even difficult, as there will be a heightened demand for information and situation reports while at the same time clinical systems that usually provide information are likely to be prejudiced by excessive demand, pressure on staff and staff sickness. This was seen during SARS in Hong Kong and Toronto where public health staff were too busy managing the outbreaks and producing situation reports to undertake the kind of surveillance envisaged in Table 2 [18,19]. There is a particular need to undertake targeted surveillance, answering key questions that will guide or trigger action, for example: 'Has the virus arrived in our country?'; 'What is the case fatality rate?'; 'Are antivirals helping?'; 'What is the spectrum of disease?' There is also a need to distinguish this from the vital needs of managers for more general situation monitoring, using questions such as: 'How are the hospitals coping?'; 'Are we running out of antivirals?'; 'Are fuel supplies getting through?'. These and other issues are discussed in a paper produced by the ECDC this month with advice from a specialist group from EU countries and its partners (the WHO-European Region and the European Medicines Agency) looking at the issues around how surveillance (epidemiological and virological) will function in a pandemic [20]. One of the more important arguments in the paper is for broadly separating date required for the management of health services from the gathering of crucial information for public health surveillance. Management needs to include determining if hospitals are functioning and supplies are flowing, while surveillance would be gathering and analysing information for key public health actions (for example, determining the viral genotype or estimating the case fatality rate - see Table 2).

As it involves parties and interests beyond the health sector, the ECDC has issued the Public Health Measures document for a public consultation (following discussion and amendment, the document has already been accepted by the ECDC’s health sector stakeholders, such as its Advisory Forum). Therefore, the paper is available on the ECDC’s website (http://www.ecdc.europa.eu) and debate, comments and suggestions are all welcome to influenza@ecdc.europa.eu, preferably with the subject title 'ECDC Pandemic Public Health Measures Menu' before 31 January 2008. Substantive comments will be published along with the ECDC’s responses. Comments and queries on the Surveillance in a Pandemic article are also welcome and should also be sent to influenza@ecdc.europa.eu.

References:
  1. Glass RJ, Glass LM, Beyeler WE, Min HJ. Targeted social distancing design for pandemic influenza. Emerg Infect Dis. 2006 Nov;12(11):1671-81. Available from: http://www.cdc.gov/ncidod/EID/vol12no11/06-0255.htm
  2. Germann TC, Kadau K, Longini IM, Macken CA. Mitigation strategies for pandemic influenza in the United States. Proc Natl Acad Sci USA. 2006 Apr 11;103(15):5935-40. Epub 2006 Apr 3. Available from: www.pnas.org/cgi/doi/10.1073/pnas.0601266103
  3. Inglesby TV, Nuzzo JB, O’Toole T, Henderson DA. Disease mitigation measures in the control of pandemic influenza. Biosecur Bioterror. 2006;4(4):366-75
  4. Institute of Medicine 2006 (Letter) Modeling Community Containment Washington DC 2006. Available from: http://www.iom.edu/CMS/3793/37624/37630/38059.aspx
  5. Jefferson T, Foxlee R, Del Mar C et al. Interventions for the interruption or reduction of the spread of respiratory viruses. Cochrane Database Syst Rev. 2007 Oct 17;(4):CD006207.
  6. World Health Organization. WHO Global Influenza Preparedness Plan. 2005 Annex One Recommendations for non-pharmaceutical public health measures (pages 42-46). Available from: http://www.who.int/csr/resources/publications/influenza/WHO_CDS_CSR_GIP_2005_5.pdf
  7. World Health Organization. Nonpharmaceutical interventions for pandemic influenza, international measures. Emerg Infect Dis. 2006;12:88-94. Available from: http://www.cdc.gov/ncidod/EID/vol12no01/05-1370.htm
  8. World Health Organization. Nonpharmaceutical interventions for pandemic influenza, national and community measures. Emerg Infect Dis. 2006;12:88-94. Available from: http://www.cdc.gov/ncidod/EID/vol12no01/05-1371.htm
  9. United States (2006) Department of Health and Human Services and Centers for Disease Prevention and Control. Interim pre-pandemic planning guidance: Community strategy for pandemic influenza Mitigation in the United States. December 2006. Available from: http://www.pandemicflu.gov/plan/community/community_mitigation.pdf
  10. ECDC Founding Regulation. Available from: http://europa.eu.int/eur-lex/pri/en/oj/dat/2004/l_142/l_14220040430en00010011.pdf
  11. European Centre for Disease Prevention and Control Influenza Pandemics and Severe Influenza Epidemics Interim Guide to Public Health Measures to Reduce the Impact of Influenza Pandemics During Phase 6 - 'The ECDC Menu'. ECDC October 2007. Available from: http://www.ecdc.eu.int/Health_topics/Pandemic_Influenza/phm%20.html
  12. WHO Interim Protocol: Rapid operations to contain the initial emergence of pandemic influenza. WHO Updated May 2007. Available from: http://www.who.int/csr/disease/avian_influenza/guidelines/draftprotocol/en/index.html
  13. European Centre for Disease Prevention and Control. Pandemics of the 20th century. Available from: http://www.ecdc.eu.int/Health_topics/Pandemic_Influenza/stats.html
  14. Monto AS. Vaccines and antiviral drugs in pandemic preparedness. Emerg Infect Dis. 2006;12:55-60. Available from: http://www.cdc.gov/ncidod/EID/vol12no01/05-1068.htm
  15. Influenza team (ECDC). Human influenza A/H5N1 (“pre-pandemic”) vaccines: informing policy development in Europe. Euro Surveill 2007;12(9):E070920.3. Available from: http://www.eurosurveillance.org/ew/2007/070920.asp#3
  16. General Secretariat for National Defence, Government of France. National Plan for prevention and control “influenza pandemic”. English-language version available from: http://www.grippeaviaire.gouv.fr/IMG/pdf/plan_national_version_anglaise.pdf
  17. Department of Health and Cabinet Office, United Kingdom. 2007 Pandemic flu draft framework and guidance. Available from: http://www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_073185
  18. Health Canada. Learning from SARS. Renewal of public health in Canada. A report of the National Advisory Committee on SARS and Public Health, October 2003. Available from: http://www.hc-sc.gc.ca/english/pdf/sars/sars-e.pdf
  19. Hong Kong SARS Expert Committee Report. From Experience to Action. Government of Hong Kong September 2003. Available from: www.sars-expertcom.com.gov.hk/english/reports/reports_fullrpt.html
  20. ECDC Influenza surveillance in a pandemic. Paper from an ECDC Working Group August 2007. Available from: http://www.ecdc.eu.int/Health_topics/Pandemic_Influenza/pdf/070801_Influenza_surveillance.pdf

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