Feature
Killer flu - the fight ahead
by Marilyn Head
Without anti-virals, we can do little to stop the estimated 3700 New Zealand deaths in the predicted influenza pandemic ahead. The Australians and the Canadians are preparing for it. What are we doing?
If you’re one of the hordes who have been struck down by the late onslaught of this year’s flu virus, you will have ample time sweating and shivering and hacking your way through the following fortnight at least to rue the day that you chickened out of the jab that could have prevented all that suffering.
“Chickened out” may be uncomfortably close to the truth. Recurrent outbreaks of Avian A type influenza “bird flu” in poultry in Asia are a worrying indication that your next dose of flu could be much more serious. The inevitability of a pandemic influenza was the key message delivered by Dr Alan Hay, director of the World Health Organisation’s Influenza Centre in London at a recent series of Science Masterclasses. His colleague, Dr Frederick Hayden, an expert virologist from the University of Virginia, presents an even more worrying picture of a world singularly ill-equipped to mount an effective initial response to a pandemic.
It has happened before. Genes from all three of the 20th-century influenza pandemics, including the devastating 1918 Spanish flu, which killed between 20 and 40 million* people, can be traced to an original source of avian flu carried by aquatic birds. Even more alarming is that the Spanish flu, and to a lesser extent the other pandemics, saw the highest mortalities occurring in young to early-middle-aged adults, rather than the usual “high risk” group of the very old, the very young and those with other medical conditions. It doesn’t take much to compute what the effect of losing or disrupting that part of the workforce would have on a country with an ageing population, like New Zealand.
Without an adequate stockpile of antiviral drugs, virologists warn that they are likely to be powerless to stop the rapid transmission of a novel influenza virus in its critical early stages. “There are only two ways to combat influenza,” says Hay. “By giving a vaccine that will generate an immune response specific to the antigenic makeup of that particular virus, or by administering an anti-viral drug that works by stopping the virus from replicating.” The World Health Organisation takes care of the former, relying on international collaboration in the form of a Global Influenza Surveillance Network to monitor small changes in the viruses, the antigenic “drift”, so that the annual vaccine “recipe” can be suitably adjusted.
But, he warns, “It cannot prepare us for an antigenic shift – in other words, a dramatically new virus. To manufacture a vaccine specific to a whole new subtype is very difficult and will take time – at least six to 12 months and possibly longer.”
Regulatory issues present even more of a challenge. “The new technologies necessary to make these sorts of vaccines are enmeshed in complex intellectual property and patent issues: sorting out the licensing problems is already something of a bureaucratic nightmare, even without the stress of facing a pandemic.”
In the absence of an effective vaccine, anti-viral drugs would be the first line of defence in the initial response to pandemic influenza. If administered quickly, they could give a “breathing space” to allow time for a specific vaccine to be developed. The bad news is, however, that there are simply not enough of these drugs to go around. Of the four anti-virals currently available, only one is considered to be effective in most situations – and only one factory in the world makes it, producing around seven million doses a year.
But surely in a global crisis other sources would be found? It is not as easy as that, according to Dr Lance Jennings, New Zealand’s foremost influenza expert. “Manufacturing anti-viral drugs is a highly specialised process, using complex equipment and sophisticated techniques – it takes years to build up that sort of capability. Making anti-virals available OTC [over the counter] is more likely to encourage the commercial development of alter-native drugs and suppliers.”
In the meantime, having a stockpile is the only means of guaranteeing access to the drugs in a large outbreak, and it’s a strategy that many countries, including Australia, are adopting. But there is a catch. Anti-virals are expensive and currently have a limited shelf life of only five years, although a powder form viable for up to 20 years is being developed. A significant investment is needed to both initiate and maintain a stockpile. On the other hand, recent modelling work by the Ministry of Health predicts that in New Zealand the “inevitable” pandemic would affect up to 35 percent of the population. Without the protection of anti-virals, little could be done to prevent the anticipated 3700 deaths and 16,000 hospitalisations. What price are we prepared to pay for health insurance?
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