Thousands of birds are being culled in the Danube Delta. A Romanian village has been sealed off in case the deadly H5N1 avian flu virus has reached it. The virus has been identified positively in dead birds from a Turkish farm on the Aegean Sea. And the transcontinental migration season for birdlife — infected and otherwise — is in full swing.

It is not hard to depict the steady westward advance of Asian bird flu in chillingly cinematic terms; nor to conclude that Europe will soon be one vast hot zone, reeling from an overdue pandemic biologically similar to the one that killed up to 40 million people in 1918. But such a conclusion would be unfounded. This virus has not yet mutated into a form that can be transmitted by humans to humans, and may never do so. In that event it would remain a serious veterinary and economic threat, especially in South-East Asia, while going down in human history as an exceedingly close shave.

A more likely scenario, endorsed by the World Health Organisation, posits the gradual mutation of the H5N1 virus over an uncertain period, probably of years rather than months. It would then trigger a massive public health emergency to which all countries would be vulnerable but for which none is yet properly prepared.

The NHS does have a “UK Influenza Pandemic Contingency Plan” that is realistic about how such a pandemic might spread and about the resources available to fight it. But these resources are inadequate. They consist of a putative stockpile of 14.6 million doses of the antiviral drug Tamiflu, and the phased production of an avian flu vaccine. At the present rate it will take at least two years to build up a Tamiflu stock of this size and the effectiveness of the drug is unproven, not least because a form of the virus able to jump from human to human may be more resistant to it than HRN1 is. For the same reason, there is little point in mass-producing a vaccine until the virus it is intended to combat has been precisely identified.

The ideal solution would be to ensure that enough manufacturing capacity were available to produce, within weeks of identifying the virus, enough vaccine to ensure “herd immunity”. But the obstacles are immense. Stringent planning requirements mean it would take two years at least to bring a new vaccine factory online, and without a public commitment to buy the vaccine there is little incentive for manufacturers to boost capacity.

In this context, the call from Markos Kyprianos, the EU Health Commissioner, for all vulnerable groups to receive the annual flu vaccine this winter appears alarmist. But government commitments to funding mass annual vaccination programmes would at least create extra manufacturing capacity that could switch to producing significant quantities of avian flu vaccine when required. The makers of Tamiflu and similar drugs should, meanwhile, be encouraged to license their production worldwide. This is not the time to panic about bird flu, nor for complacency. It is the time for farsighted preparation.