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UCD Professor launches expert advice report on Pandemic Influenza - Ireland stockpiles antiviral drugs in contingency plan

Posted: 19 January 2007

An expert group, chaired by Professor William Hall, Director of the National Virus Reference Laboratory, and UCD School of Medicine and Medical Sciences, has published a new report in preparation for the impact of a pandemic influenza outbreak, which could reach Ireland. In a briefing on the report, Pandemic Influenza Preparedness for Ireland 2007, this week Professor Hall outlined the steps already taken and the recommendations, which need to be implemented in order for Ireland to be ready to deal with the impact of a major outbreak.

In the past 300 years there have been at least ten influenza pandemics and three of these have occurred in the last ninety years. The Spanish Flu in 1918 was caused by an avian influenza virus and resulted in an estimated 40 million deaths. The Asian Flu in 1957 caused 2 million deaths and the 1968 Hong Kong Flu is believed to have been responsible for 1 million deaths.

The WHO (World Health Organisation) produced guidelines in 1999 and recommended individual countries prepare a specific plan to address the needs of their population. In response, the Minister for Health and Children, established an expert group to oversee the preparation of a national plan. Its first report was published in 2001 and the group has constantly revised and updated its recommendations based on new developments in the field and the changing dynamics of virus infections throughout the world.

In 1997 a new strain of avian influenza – H5N1 – appeared in Hong Kong. Since it first emerged, H5N1 has infected 263 individuals and caused 157 deaths in ten countries. Some experts believe that this virus, or a variant thereof could precipitate the next pandemic.

At present there is an active surveillance programme for influenza in Ireland. This Sentinel Surveillance Programme is a collaboration between the National Virus Reference Laboratory (NVRL) at UCD, the Health Protection Surveillance Centre (HPSC) and the Irish College of General Practitioners (ICGP). Samples collected from all respiratory illnesses in 24 sentinel centres around the country are sent to the NVRL and analysis for the presence of influenza. The NVRL is a WHO reference laboratory and is a member of the UK Influenza H5 Laboratory Network. Within the network new diagnostic methods are developed and validated so that the most accurate tests for screening and confirmation of H5 viruses are employed. The NVRL has participated successfully in two Quality Assurance exercises when laboratory investigation and reporting had to be completed within 6 hours.

In addition to human surveillance, the Department of Agriculture also carries out active surveillance of poultry populations

In recent years, the pharmaceutical industry has successfully developed a new class of anti-influenza drugs – so called neuraminidase inhibitors – which have been shown to be highly effective in treating influenza. The two antiviral drugs are Tamiflu (oseltamavir) which is the first-line drug recommended by the WHO and which is taken as a pill and Relenza (zanamivir) which is inhaled.

With the introduction of modern molecular biology techniques, scientists have also been able to speed up the development of new pandemic vaccines and this has also assisted the development of novel diagnostic methods which allow the rapid detection of novel influenza viruses when they appear.

On earlier advice of the expert group, the Department of Health and Children has already purchased stocks of Tamiflu to cover 25% of the Irish population. It is intended to also stockpile Relenza to provide an additional 20% coverage. Together this is the second highest stockpile in the world and current supplies of these drugs could only treat 20% of the global population. The expert group advises that plans for their administration should be made in order of priority to prevent or reduce deaths and hospital admissions from an influenza outbreak, to prevent and reduce illness from influenza and to maintain essential services.

As part of the Irish pandemic plan, the Department of Health and Children has also procured 200,000 doses of a candidate H5N1 vaccine for use for front-line workers. In addition the Department is in the process of making advance purchase agreements to obtain any future pandemic virus vaccine with a number of vaccine-producing pharmaceutical companies. The intention is to procure enough pandemic vaccine to vaccinate the entire population of Ireland.

The expert group has prioritised healthcare staff, providers of essential services, those with high medical risk, those over 65 years of age and selected industries (e.g. pharmaceutical) to receive initial supplies of the pandemic virus vaccine.

During his briefing, Professor Hall addressed the difficulty of modelling and predicting the scale of a pandemic. “The impact and outcome of a pandemic will depend on a large number of factors which include how pathogenic the virus is, the attack rate, the severity of the clinical illness, the case fatality rate and the effectiveness of preventative measures.” The current predictive model used is based on two possible scenarios.

The first is an attack rate of 25% with a case fatality rate of 0.35, which is similar to the 1957 pandemic. With this we could expect one million cases over a 15-week period with 6,000 hospitalisations and 4,000 deaths.

The second is a “worst case” scenario based on the 1918 outbreak with a 50% attack rate and a fatality rate of 2.5%. Such a catastrophic event, with over 2 millions cases of disease, would result in some 78,000 hospitalisations and almost 53,000 deaths. Professor Hall stressed that these theoretical figures do not take into account the important effect of antiviral treatment which would significantly reduce the impact of the pandemic in Ireland. Nor do they account for the rapid response which would be made possible by the implementation of the National Plan for Pandemic Influenza. “Ninety years on we have made gigantic leaps in our ability to effectively and directly to treat influenza, in our ability to monitor the movement of disease and in our capacity to deal with outbreaks” he said.

The full report of the expert group covers surveillance, detection and situation monitoring, public health response, utilisation of appropriate drugs, non-pharmaceutical public health interventions, case management and infection control. It summarises the current situation regarding avian flu and the implications for human health.

Recommendations on the implementation of the action plan, communications and legislation from the expert group’s report in 2002, A Model Plan for Influenza Pandemic Preparedness have been fed into the National Plan for Pandemic Influenza (2007).

Under WHO advice, actions are being taken throughout the world to strengthen national preparedness, reduce opportunities for a pandemic virus to emerge, improve early warning detection systems, delay global spread, and accelerate vaccine development.

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