Straits Times 24 Jan 09;
An international immunology symposium this week saw 400 scientists gathering to discuss how the body's defences affect conditions ranging from cancer to ageing. Liaw Wy-Cin speaks to some of the experts on a possible flu pandemic.
A FLU pandemic - which many scientists fear could strike at any time and kill millions of people - is unlikely to happen, says one infectious diseases expert.
Professor Jonathan Yewdell, from the prestigious US National Institutes of Health (NIH), said that the biggest disease threat - virulent bird flu viruses rampant in poultry and wild fowl - was unlikely to mutate to a form that would spread easily among people.
On top of that, many countries have been preparing for years to deal with a potential pandemic. Also, scientific advances would translate into speedy vaccines which would undermine an outbreak before it swelled to the size of pandemics of the past century.
A pandemic, which could be caused by a mutated strain of the avian influenza virus, could hit up to 70 million people and cost US$3 trillion (S$4.5 trillion), according to the United Nations and World Bank. It is also considered one of the world's biggest threats.
Since 2003, the virulent H5N1 strain of bird flu has infected about 400 people, killing around 250. It is endemic in many parts of Asia.
But Prof Yewdell, chief of cellular biology at the NIH Laboratory of Viral Diseases, believes a pandemic is not likely.
Immunology is the study of the body's response to foreign entities such as viruses. The NIH, which leads biomedical sciences research in the US, does frontline work on fighting bird flu and other dangerous viruses.
Before a pandemic can occur, the virus has to mutate to a stage where it can spread easily from person to person, said Prof Yewdell, who took part this week in a symposium here organised by the Singaporean Society for Immunology.
But most bird flu cases so far have been through direct contact with infected birds, though there have been rare cases of human-to-human transmissions.
While he concedes that bird flu could one day mutate to a form where it spreads among people, he believes medical science and international political cooperation will stop it in its tracks.
'We are in a much, much better place today than in 1968 when we had the last flu pandemic,' he said.
'In the past, it took a few years to sequence the genome of a virus. Now, we can do it overnight.'
The information allows vaccines and treatments to be developed very quickly - within months, compared to years in the past.
Other experts, however, do not share Prof Yewdell's optimism.
The head of Duke-NUS Graduate Medical School's emerging infectious diseases research programme, Professor Duane Gubler, said: 'If you look at history, we have done a very poor job. We have failed miserably to respond to epidemics, the most recent being the Sars epidemic.'
The Severe Acute Respiratory Syndrome epidemic in 2003 saw 8,096 people infected and 774 killed.
'The H5N1 virus is becoming more widespread in the world, with high transmissibility among birds of various species. And it can take very small genetic changes for the virus to increase its transmissibility.'
The clinical director of Tan Tock Seng Hospital's Communicable Disease Centre, Associate Professor Leo Yee Sin, said that, at the moment, science could not predict when and where the next pandemic is likely to happen.
'Although there have been ongoing case reports of human H5N1 infection, there is still a significant barrier preventing cross-species infection from bird to human,' she said.
'But among those infected, the mortality of human H5N1 cases remained high despite the use of antiviral drugs.'
Dr Martin Hibberd of the Genome Institute of Singapore agreed that the current bird flu virus did not look as if it would cause a pandemic.
'But there are still a lot of unknowns. We don't know if this virus will someday change to become as contagious as the common flu, and yet remain as deadly as it is now,' said Dr Hibberd.
Another potent weapon in the global fight against a pandemic is preparedness, stressed Prof Yewdell.
'The government in Singapore clearly gets the message that research is important in this fight against bird flu,' he added.
Singapore has put together a ministerial committee to tackle bird flu and its health, social and business impact. Apart from strategies like stockpiling medicine, Singapore has put in place a suite of non-medical measures ranging from enforcing quarantine orders to supplying necessities such as food and power.
Officials regularly test local poultry, wild birds, pets and imported birds and eggs. A contingency plan for culling infected birds has also been drawn up.
Since 2006, the Government has also held at least seven contingency drills to simulate a pandemic here and rehearse containment measures and responses.
