Flu pandemic planning

Contents [show|hide]

Introduction
Background
Seasonal vs pandemic influenza
Current outbreak of H5N1 (avian influenza)
Contingency planning
Rapid response and containment
UK and international alert levels
National and international plans
Local plans in the Thames Valley area
Tabletop exercises in the Thames Valley area
Related links

Introduction

There is currently international concern that an influenza pandemic is imminent. This article outlines the background to this concern and what steps are being put in place to address it.

Pandemic influenza is a strain of influenza A which usually derives from an animal reservoir. The strain has to mutate or recombine with other strains to become capable of (a) infecting humans; and (b) being easily passed between humans (human-human transmission). Because this strain of influenza is novel in humans it is passed rapidly through populations - which are unlikely to have significant prior immunity - and gives rise to a world-wide 'pandemic'.

Clinical attack rates for a pandemic influenza may be 25-50% of the population, with mortality in affected individuals in the region of 0.37-2.5%. Initial mortality rates before a strain becomes well adapted to humans may be much higher (e.g. >50%).

Historically flu pandemics have occurred with a frequency of 11-42 years. The last pandemic was in 1968/9, so it is thought another may be due soon.

Seasonal vs pandemic influenza

Flu pandemics can be distinguished from 'seasonal' influenza epidemics in a number of ways:

pandemic influenza may occur during any season
seasonal epidemics usually occur in winter
pandemic influenza may affect any age group - including young healthy adults (who usually make up the bulk of a nation's workforce)
seasonal epidemics usually affect the young, elderly and immunocompromised predominantly
pandemic influenza virulence (ability to infect and cause severe illness) can vary and is difficult to predict prior to significant numbers of clinical cases
pandemic influenza usually occurs worldwide once every few decades
seasonal influenza is usually annual and outbreaks are usually limited to smaller geographical areas
because a number of adaptations need to occur for an influenza strain to become a pandemic strain, there is an inevitable delay in being able to produce vaccine to combat pandemic flu
a seasonal influenza vaccine is usually available prior to significant numbers of clinical cases

Current outbreak of H5N1 (avian influenza)

The emergence of a strain of bird flu (avian influenza) - H5N1 - in the last few years which is affecting birds in Asia, Europe and Africa, and a small number of humans in SE and Central Asia and the Middle East has sharpened the minds of public health planners and contingency plans are rapidly being drawn up to cope with a possible pandemic (see Contingency planning, below).

Whilst the first step required for a pandemic influenza has been fulfilled (transmission between animals and humans), at this stage there is no evidence of sustained transmission between humans, so this is not yet a pandemic strain. However, the fear is that with increasing numbers of poultry affected across the world it may be a matter of time before the virus adapts better to humans.

Countries reporting poultry cases of H5N1 to date

Afghanistan, Albania, Austria, Azerbaijan, Bosnia and Herzegovina, Bulgaria, Burkina Faso, Cambodia, Cameroon, China, Cote d'Ivoire, Croatia, Czech Republic, Denmark, Djibouti, Egypt, France, Georgia, Germany, Greece, Hong Kong, Hungary, India, Indonesia, Iran, Iraq, Israel, Italy, Japan, Jordan, Kazakhstan, S Korea, Laos, Malaysia, Mongolia, Myanmar, Niger, Nigeria, Pakistan, Palestinian territories, Poland, Romania, Russia, Serbia and Montenegro, Slovakia, Slovenia, Spain, Sudan, Sweden, Switzerland, Thailand, Turkey, Ukraine, United Kingdom, Vietnam

Countries reporting human cases of H5N1 to date

Azerbaijan, Cambodia, China, Dijibouti, Egypt, Indonesia, Iraq, Thailand, Turkey, Vietnam

Sources: OIE, WHO, Promed

DEFRA has set up a telephone helpline (08459 33 55 77) for members of the public if they find birds in the UK which which appear to have died from an unexplained cause. Single deaths should not be notified unless they are fowl (swans, ducks or geese).

Contingency planning

Actions proposed to prepare for and manage an influenza pandemic are based on the following principles:

surveillance - for new cases in animals +/- humans
infection control - including basic hygiene measures, isolation of cases (voluntary if possible), prevention of large-scale gatherings, restriction of travel between infected and non-infected areas (where possible)
medical prophylaxis/treatment - use of antivirals and vaccine (when available), both according to predetermined priorities in the event of insufficient supply
staff protection - plan for a diminished workforce both in the healthcare sector and elsewhere
overburdening of healthcare facilities - inevitable in a full-scale pandemic, due to staff illness, presentation of new influenza cases and redeployment, e.g. for mass vaccination
health promotion - dissemination of the above messages to health professionals and the general public

For a more detailed discussion on the measures proposed please see the current flu pandemic plans, below. Although these plans mainly deal with NHS bodies, all organisations - public or private, healthcare or non-healthcare - will potentially be affected.

Of particular note is that whilst prison healthcare has recently become the formal responsibility of the local NHS Primary Care Trust, the Home Office and Prison Service are also involved in contingency arrangements. A recent Prison Service Instruction (PSI) has been issued on pandemic planning in prisons:

PSI 29/2006 - Contingency planning for pandemic influenza (Word document 289kb, HM Prison Service, Oct 2006)

Rapid response and containment

The WHO has recently started consulting on a strategy to try to avert an imminent flu pandemic by rapid treatment of cases and prophylaxis. A paper last year set out one method by which widespread prophylaxis may be able to prevent a pandemic.

WHO protocol for rapid response and containment (WHO, May 2006)
Ferguson et al, Nature DOI: 10.1038/nature04017 [?] (Nature, Sep 2005)

UK & international Alert levels

Actions recommended depend on the stage of a pandemic and can be divided up by Alert level:

Current DH Alert level (0-4): 0
No cases anywhere in world (i.e. of human infection with a new subtype capable of spreading easily between humans)
Current WHO Pandemic Alert level (1-6): 3 More...

Human infection with a new subtype but no human-to-human spread or at most rare instances of spread to close contacts

(See DH/WHO pandemic plans, below, for more information on Alert levels.)

National & international plans

Local plans in the Thames Valley area

Influenza planning in the Thames Valley has been co-ordinated by a Thames Valley Influenza Pandemic Committee (TVIPC, SHA level), with three County Committees (Berks, Bucks and Oxon) sitting beneath this to help develop local plans. A Thames Valley SHA plan and plans for each county/locality area exist, and most NHS organisations within the region now have detailed operational plans. Importantly, it is recognised that pandemic planning is an ongoing process and plans will evolve as new information becomes available. With the reorganisation of the SHAs, South Central SHA (the result of the merger between TVSHA and Hampshire/Isle of White SHA) is now continuing the planning role. The most recent pandemic influenza plans for the South Central area can be found on the NHS South Central website.

Tabletop exercises in the Thames Valley area

The first table-top exercise of the draft plan for the health sector took place in the Thames Valley on 28 September 2005. The aim of this exercise was to raise awareness of the potential problems faced in a pandemic and attempt to iron out any major faults with the plan.

It was clear from the exercise that whilst there could be potentially large upsets to essential services early on in a pandemic, the basic messages of encouraging self-care, rigid infection control and hand hygiene measures, and timely dissemination of this information to the public and healthcare professionals, could avoid many problems.

Much work has gone on since the last exercise of the plans, and a further test was carried out on 4 April 2006. The scenarios used in this exercise are available below:

Flu pandemic tabletop exercise April 2006 (pdf, 58kb)

Flu pandemic planning

Introduction

Background

Seasonal vs pandemic influenza

Current outbreak of H5N1 (avian influenza)

Countries reporting poultry cases of H5N1 to date

Countries reporting human cases of H5N1 to date

Contingency planning

Rapid response and containment

UK & international Alert levels

National & international plans

National - latest plans

National - other plans

International

Local plans in the Thames Valley area

Tabletop exercises in the Thames Valley area

Related links

Major health agencies' general information websites

Information for public/lay audience

Updates on clinical presentation and management of human H5N1

Other resources

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