Exactly a year ago (randomly), I was sitting at home feeling rubbish, after catching Freshers’ Flu. I wrote a blog entry about how inconsiderate it was to come in to work whilst infectious, etc etc, and wrapped up with a note that we were overdue for Something Nasty™ to be coming our way.

Something Nasty™ is on the way.

The H5N1 strain of influenza is now widespread throughout the avian populations of Asia, and is moving westward; most recently it has been detected in Romania. H5N1 is “bird flu” – it infects and spreads amongst birds, but what makes it special is that it can also infect humans. And of those it infects, fully 30% do not survive, even with modern medical support. Currently, H5N1 strains can not be transmitted between humans, but it’s only a matter of time before this, or any one of the myriad other avian viruses becomes easily transmissible, and then all hell will break loose.

We are extremely poorly prepared for any pandemic disease. We have enough trouble with epidemics of less transmissible diseases such as SARS. The last flu pandemic was Hong Kong Flu, in 1968. This was caused by mixing of human and avian flu, and 750,000 people died. The last time an avian flu became capable of spreading amongst people directly was 1918, when somewhere between 50 and 100 million people died.

Today, with the increased global mobility afforded by cheap air travel, it is believed that the disease would spread from city to city twice as rapidly as it did in ‘68. It takes approximately 250 days to develop and produce a vaccine, but the prediction is that a new pandemic would be global within 180 days today. We would have only a few weeks’ warning of the impending disaster, and perhaps less if it originates somewhere with less-than-transparent reporting (China and Vietnam are particularly reluctant to share information). It’s not even clear if we could create a vaccine – the H5N1 virus is so deadly to chickens that it creates major problems: influenza vaccines are made using chicken eggs, and the virus kills them.

Antiviral therapy such as Tamiflu is only effective within the first 48 h of infection, and even then is far from a cure; it might increase your chances of survival, but its effectivity against such a potent killer is hard to judge.

So what would happen, if a new, transmissible influenza virus begins spreading through Vietnam or China?

1. It is likely to be a number of days between infection and the onset of symptoms. Carriers are probably infectious for at least some of this time.
2. The virus can probably be expected to reach a major city within a week or two. Depending on the country of origin, the health services may or may not be aware of the outbreak already.
3. The local government is likely to deny the problem, and then deny the scale of the problem. The true scale of the problem doesn’t become evident for some weeks, as the number of cases gradually rises, reaching a peak several weeks after the first infection.
4. Almost immediately, the virus is spread from this first city to regional hubs, and probably (depending on the city) internationally.
5. By this point, the international community should be aware of the situation. Large supplies of antivirals will be delivered rapidly to the initial city of infection, hopefully helping to bring the situation in that area under control. The West will begin urgently developing a vaccine for this strain.
6. Some initial restrictions on travel will probably be enforced at this point; refusing entry to travellers from the centre of infection, screening for symptoms on arrival. These will be essentially ineffective.

1. Outbreaks will become clear in the regional hubs; Sydney, Bangkok etc. Response to these outbreaks varies by country; some will be effective, some will not.

   And here we reach the critial point. Are the local responses strong enough to contain the virus? Or does it spread far enough that health services are overwhelmed? Already, isolates of H5N1 which are resistant to Tamiflu have been found – and much of the response to H5N1 depends on being able to contain the spread with Tamiflu.

   Governments will have to make some severe choices about the degree to which they are willing to restrict liberties, to protect their population. All the debate recently about the restrictions imposed in London following the July 7 bombs will pale into insignificance when we are confronted with a ban on international and interregional travel, and on congregations of more than a few people. The damage to the economy will be staggering.

   The current predictions for the number of deaths from a disease on the order of the 1918 Spanish Flu range from a conservative 7.5 million, to the order of 180-360 million if it progresses similarly to the 1918 flu. “Pandemic” doesn’t go far enough, “apocalypse” is closer to the result of that kind of mortality on human society.