|
Everyone seems to have got into a flap about bird flu lately. Is there any reason to panic? No. It is disappointing but not surprising that autumnal migrations have spread the deadly H5N1 flu strain from Asia to birds in south-east Europe (certainly in Romania and Turkey and probably Greece and Macedonia too). There is no evidence the virus has made the genetic mutation everyone dreads: changing to a form that would spread between people.
Is it inevitable that, sooner or later, the avian flu virus will "go human" and start a pandemic?
Virologists say there will eventually be another pandemic, though there is no way of predicting whether it will be relatively mild like Asian flu in 1957 and Hong Kong flu in 1968, which killed an estimated 1.0m people each, or catastrophic like the 1918 Spanish flu that killed 50m. A pandemic starts when an avian flu strain mutates -- or mixes with human virus -- and transmits through a population that has no immunity to it.
The H5Nl strain, responsible for more than 100m bird deaths in Asia, is the most likely candidate because it is so widespread and, on the rare occasions when it infects a human, so virulent. If we are lucky H5N1 may never undergo the random genetic changes required to go human. But another avian virus will, sooner or later.
When and where is a pandemic most likely to begin?
The timing of its start is completely unpredictable, though some experts say on the basis of limited genetic surveillance data that H5Nl is unlikely to go human over the next few months. Asia remains the most likely location because it has so many birds and people living in close proximity.
If H5N1 does go human, how fast will the pandemic spread?
Mathematical modelling shows there is a small but realistic chance of snuffing out a newly humanised strain of avian flu before it even starts a pandemic. Excellent surveillance and rapid administration of Tamiflu anti-flu tablets could stop a local outbreak.
Otherwise the virus could spread around the world within a few Weeks. An international travel ban would make little difference, because there would have to be some exceptions and flu is so infectious.
Will there be enough time to develop, manufacture and administer a vaccine against the pandemic strain before it spreads around the world?
Certainly not. Even using the best new technology and huge resources, it would take four to six months to isolate and characterise the new viral strain, grow seed stock, start manufacturing, prove the vaccine works in clinical trials, license it and deliver to the field. By then millions might have died. But past pandemics have occurred in two or three waves, over about a year, so a crash programme to develop a vaccine would still be worthwhile. (Exclusive to FE under syndication service)
|