Taking the panic out of pandemic
[ The University of Melbourne Voice Vol. 3, No. 9
10 November - 8 December 2008 ]
University of Melbourne researchers are helping to prepare for the next wave of flu, JANINE SIM-JONES reports.
Ninety years ago Australian troops returned from France carrying with them deadly baggage. Spanish flu was rampaging across Europe and Australian scientists began the race to develop a vaccine. Fast forward to 2008 and Australian scientists are again planning for a major influenza epidemic.
It could be a pandemic equally as virulent as in 1918 but with the ability to spread more rapidly thanks to a globe-trotting population with easy access to international air travel.
Professor Terry Nolan, Head of the University of Melbourne’s Melbourne School of Population Health is the one of the leaders of Australia’s research effort to minimise the impact of future pandemic outbreaks. He says it’s not a matter of if a pandemic strain of flu will develop but when.
“There certainly will be another pandemic,’’ says Professor Nolan. “There were three in the last century and in previous centuries we have good historical data which shows us that there have been similar pandemics going back several hundreds of years. Although they did not have the sophisticated virology back then these deaths can’t be attributed to the plague or other known causes of death, so the inference is that they most likely were influenza pandemics.
“Because human travel occurs so much more readily, the ability of a mutated strain of a virus to be disseminated around the world by transport and human movement is much greater. Also, the proximity and density and size of domestic bird flocks are at a much higher level than ever before because there are so many more humans.”
However, on the plus side, Professor Nolan says that, unlike in past pandemics, government and health authorities worldwide are well prepared. The emergence of the H5NI influenza A bird flu virus and its first human deaths in 2003 together with the SARS epidemic, shocked many authorities into action. Since then Australia has been a world leader in pandemic planning, with governments, health authorities and the research community working together to ensure a coordinated response to an influenza outbreak.
The University of Melbourne and three other universities have formed a national consortium – backed by the National Health and Medical Research Council – of mathematicians, medical specialists, biologists and infectious disease policymakers, whose work is helping inform Australia’s pandemic plan.
Professor Nolan and Professor Graham Brown, from the University of Melbourne’s Nossal Institute of Global Health, are principal investigators of the work done at Melbourne as part of the National Capacity Building Program in Infectious Disease Modelling.
Melbourne School of Population Health’s Dr Jodie McVernon and Dr James McCaw are involved in major modelling projects related to the size of vaccine and anti-viral stockpiles and public health measures to contain an outbreak. The University – with the Murdoch Children’s Research Institute – is a major partner in the Vaccine Immunisation Research Group (VIRGO) which led clinical trials of a candidate pandemic vaccine developed by CSL.
Meanwhile, Professor John Mathews, also from the Melbourne School of Population Health, is analysing historical data in a bid to better understand the causes of the 1918 Spanish flu pandemic (story below).
Professor Nolan says the pandemic modelling work in Australia is concentrating on three major aspects: the use of anti-viral drugs such as Tamiflu® and Relenza®; public health measures such as school closures and border control; and vaccination.
“Although we have clinical trials of a vaccine, the modelling tells us the best way to use it,’’ he says. “We model the impact of varying the dosage regime to optimise benefit and availability of vaccine for as many people as possible.
“To test drugs and vaccines you usually have a randomised control trial but you can’t do that with a pandemic because you don’t really know what is going to happen until it strikes.”
Professor Nolan says Panvax®, the vaccine developed by CSL against the H5N1 virus, has been successful in clinical trials and shown to be particularly effective in children. It has been registered by the Australian Government’s Therapeutic Goods Administration and is part of Australia’s stockpile, along with vaccines made by larger international pharmaceutical companies.
However, when a pandemic arrives the virus is likely to have mutated so the stockpiled vaccines will provide only partial protection and act as stop-gap protection during the four or five months it will take to develop a new vaccine specific to the mutated strain.
Professor Nolan said the process for developing and trialling Panvax® in the wake of the initial bird flu outbreak was great preparation for responding to future pandemics.
“The whole pathway for developing vaccines is established and ramped up in a way it wasn’t before,’’ he says. Dr Jodie McVernon and her colleagues’ research has focused on the ‘contain’ and ‘sustain’ phases of pandemics, recommending the best ways of limiting the virus spread until a pandemic-specific vaccine becomes available. This includes modelling to determine how anti-viral drugs should be used in the early stages of an outbreak.
In particular, the research has examined the effectiveness of intensive contact tracing – tracking down as many of the people who may have been in contact with an infected person and providing them with anti-viral drugs even if they don’t have symptoms.
Dr McVernon says many experts have shied away from the concept of contact tracing, a method commonly used to stop the spread of sexually transmitted diseases, because it is considered too difficult. But the modelling was showing that it could be extremely effective in slowing a pandemic’s pace.
“If an infected person has a conversation with 20 people in a day and we can find only 10 of them it can make a very big difference, assuming that the drugs work,’’ Dr McVernon says.
Similarly, the research was also showing that while use of antiviral drugs to protect front-line health care workers in the first few months used a substantial proportion of the stockpile, this did not impede control efforts or the ability to treat influenza sufferers.
Dr McVernon says as well as providing anti-virals in the early stages, it is important that governments stockpile more than one drug to overcome the problems caused by the development of drug-resistant strains of flu.
“If you use two drugs and the virus becomes resistant you have a safety back-up,’’ she says.
“You might use one drug for treatment and another for prevention to delay resistance from emerging.”
Dr McVernon recalls working in the UK at the time of SARS and how critical that outbreak was in focusing authorities on the importance of planning for public health emergencies. Since then there has been a major international effort to build the world’s capacity to combat a pandemic. But in times of economic crisis and with widespread concern about other public health issues such as obesity and diabetes, Professor Nolan says governments must not relax their focus on pandemic prevention.
“The state of preparedness and planning needs to be ongoing,’’ he says. “The anti-viral stockpile has a ‘use-by’ date and vaccines also have a shelf-life so there will be questions about their replacement.
“We also need to keep our human systems up to date and in tune with new thinking and development internationally.”
And despite the easing of media attention on the bird flu risk, Professor Nolan says little has changed in terms of the threat it poses.
“The media activity has little to do with the biological human risk,’’ he says.
“It is just as high as it was two years ago, the media has found other things to be interested in, but the underlying risk remains the same and the need to pay attention to it is just as strong.”
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