Pandemic Flu

What is flu?

Flu is an acute respiratory illness caused by infection with an influenza virus. There are three types in all with influenza A and influenza B causing the majority of infections. A third type, influenza C, is rarely reported as a cause of human illness.

Flu is characterised by sudden onset of symptoms which include a temperature of 38ºC or more with a dry cough, headache, sore muscles and sore throat. Cough is often severe and protracted, but otherwise the disease is self-limiting in those without underlying illness, and recovery is usually within 2 to 7 days.

What is avian flu?

Avian influenza (“bird flu”) is an infectious disease of birds caused by type A strains of the influenza virus. It can affect all species of birds and other animals and can very rarely infect humans.

Infection causes a wide spectrum of symptoms in birds, ranging from mild illness to a highly contagious and rapidly fatal disease resulting in severe epidemics. The avian influenza strain which is causing most concern at the moment is A/H5N1.

Further information is available on www.dohc.ie/issues/avian_flu and on www.birdflu.ie

What is pandemic flu?

Pandemic flu is a type of influenza that spreads rapidly to affect most countries and regions around the world. It can occur at any time of the year and occurs due to the emergence of a new flu virus, which is very different from the usual viruses that cause seasonal flu. As it will be a new virus no one will have immunity to it.

How is pandemic flu different from seasonal flu?

It spreads in the same way as seasonal flu, but as no one will have immunity to it, it will spread very quickly throughout the population and will cause more serious illness before a vaccine becomes available. Influenza whatever its type is a highly infectious illness. Viruses are easily passed from person to person when an infected person talks, coughs or sneezes and expels the virus into the air. You can also catch the virus through touching an infected person or surface contaminated with the virus, and then touching your or another person’s face.

What is the connection between bird flu, seasonal flu and pandemic flu?

One way pandemic flu can occur is if bird flu mixes with human flu and creates a new strain of virus that can spread easily from human to human. Experts fear that the bird flu virus (A/H5N1) causing outbreaks around the world could trigger the next pandemic for several reasons.

Firstly, it has already demonstrated an ability to infect people and cause severe disease – one of the key characteristics of a pandemic strain. Secondly, this particular virus has a documented ability to mutate (change) and to acquire genes from viruses infecting other species. Experts fear that the virus could, either adapt, giving it greater affinity for humans, or exchange genes with a human flu virus, thereby producing a completely novel virus capable of spreading easily between people, and causing a pandemic.

How serious is the current pandemic risk?

The risk of pandemic influenza is serious. With the H5N1 virus now firmly entrenched in large parts of Asia and some regions in Europe, the risk that more human cases could occur will persist. Each additional human case gives the virus an opportunity to improve its transmissibility in humans, and thus develop into a pandemic strain. The recent spread of the virus to poultry and wild birds in new areas further increases opportunities for human cases to occur. While neither the timing nor the severity of the next pandemic can be predicted, the probability that a pandemic will occur has increased.

The World Health Organisation (WHO) uses six phases of pandemic alert as a system for informing the world of the seriousness of the threat. These phases reflect the progression of an influenza pandemic from the first appearance of a new flu virus to wide international spread. The current pandemic alert level is Phase 3: a new influenza virus subtype is causing disease in humans, but is not yet spreading efficiently among humans.

What is being done to prepare for pandemic flu?

On 15th January 2007, the Department of Health and Children and the Health Service Executive launched two new publications

The purpose of the National Pandemic Influenza Plan is to limit the effects of a potential pandemic and to

The National Pandemic Influenza Plan will be updated on a regular basis to reflect the most up to date advice of the expert group and international developments. Comments on the plan are welcome and can be emailed to pandemicflu@health.gov.ie and pandemicflu@maild.hse.ie

Pandemic Influenza Preparedness for Ireland - Advice of the Pandemic Influenza Expert Group outlines clinical guidance and provides public health advice to health professionals and others involved in pandemic influenza preparedness and response. This is a draft consultation document and the consultation period closed on the 30th April 2007.

The Health Service Executive has developed detailed action plans for local level preparedness for a pandemic. These action plans are based on the National Pandemic Influenza Plan and reflect the advice of the Pandemic Influenza Expert Group. These detailed action plans identify the steps to be taken in all hospitals, local health offices, ambulance areas and public health departments to prepare for the next pandemic and provide the basis for all local operational plans. Implementation will be closely monitored throughout 2008 to ensure operational plans are developed in a consistent and co-ordinated fashion across the entire health system.

Planning Assumptions

The severity of disease and the number of deaths caused by a pandemic virus vary greatly, and cannot be known prior to the emergence of the virus. Pandemics can cause large surges in the numbers of people requiring or seeking medical or hospital treatment.

A range of estimates on the potential impact of a future pandemic have been adopted for planning purposes:

These assumptions are being kept under review and may be revised in line with international advice and risk assessment.

Vaccines

At the moment there is no vaccine ready to protect against pandemic flu. Since influenza pandemics occur when a new flu virus emerges to which people have no immunity, the vaccine can only be manufactured once the new strain emerges. It is anticipated that it will take at least four-to-six months from the time a pandemic flu strain emerges to develop and manufacture a vaccine.

The plan is to purchase enough pandemic vaccine to cover the entire population as soon as a vaccine is available. The Health Service Executive is actively pursuing an advanced purchase agreement for a pandemic strain vaccine and the procurement process is underway.

Meanwhile, the HSE has purchased sufficient H5N1 vaccine for 200,000 people (i.e. 400,000 doses). International experts consider that a stockpile of H5N1 vaccine could be used as a first line of defence for key health care workers and other essential workers while a vaccine against the exact pandemic influenza strain is manufactured.

Antivirals

The main treatment for pandemic influenza is antiviral drugs. Antivirals can shorten the duration of the disease and alleviate symptoms. They are not usually considered effective after 48 hours from the onset of illness.

An emergency supply of over 45,000 treatment packs of antivirals (Tamiflu®) was purchased in 2004. A further 1 million treatment packs of antivirals (Tamiflu®) have been stockpiled. This quantity is sufficient to treat 25% of the population.

Tamiflu® capsules are not suitable for young children. The health services have, therefore, also stockpiled a supply of the active pharmaceutical ingredient (API) which will allow for treatment of almost 110,000 children.

Recommendations for the stockpiling of antivirals are kept under constant review by the Pandemic Influenza Expert Group. The Expert Group advised that a quantity of zanamivir (Relenza®) should be stockpiled in addition to oseltamivir (Tamiflu®). 706,000 courses of Relenza® have now been stockpiled by the HSE.

The quantity of antivirals in stock or on order is enough to treat almost 2 million people. This compares very favourably with other countries across Europe and beyond.

Plans for the distribution of antivirals in the event of a pandemic are being finalised. In a pandemic situation antivirals will primarily be used for treatment of influenza cases:

As the definition of risk is likely to change over time, recommendations for the use of antivirals will be kept under review by the Pandemic Influenza Expert Group. The decision making process will be guided by relevant expert advice from the European Commission and the World Health Organisation.

Business Continuity Planning

On 28th February 2007, the Minister for Enterprise, Trade and Employment launched Business Continuity Planning - Responding to an Influenza Pandemic. The guide is aimed at increasing the level of awareness among Irish businesses of the need to plan for an influenza pandemic. It contains a checklist which businesses can use to plan effectively for such a situation as well as including ten illustrative case studies across various sectors.

Influenza Pandemic Preparedness in Ireland, Joint Assessment Report, 2007

On 26th November 2007, the Department of Health and Children and the Health Service Executive published an assessment report on how Ireland is prepared to deal with an influenza pandemic. The report was prepared by a joint team of experts from Ireland and representatives from the European Centre for Disease Prevention and Control (ECDC). The assessment visit took place between February 28th and March 1st 2007. The report highlights areas where significant progress has been made and also points out areas where further work is needed.

See the press release issued on 26th November 2007.

Download the Influenza Pandemic Preparedness in Ireland Joint Assessment Report 2007.

Sources/ Relevant Websites