A bird flu pandemic will hit Britain - but not necessarily this winter, the
chief medical officer has said.
Sir Liam Donaldson said a deadly outbreak would come when a strain of bird
flu mutated with human flu.
He told the BBC's Sunday AM show it would probably kill about 50,000 people in the UK, but the epicentre of any new strain was likely to be in East Asia.
The UK has so far stockpiled 2.5m doses of anti-viral drugs - and may restrict travel if there is an outbreak.
New vaccine
On Saturday, UK tests confirmed a case in Romania of a strain of bird flu
which is potentially deadly to humans, sparking fears avian flu could spread
to the UK through migrating birds.
A pandemic would occur if this strain of bird flu mutated with human flu -
which spreads very easily - to create a new strain.
He said it was "less likely" that any new flu strain would come this year.
However he said that if the flu first emerged in another part of the world it would give UK scientists time to try to create an effective vaccine against the virus before it arrived in the UK.
"We can't make this pandemic go away, because it is a natural phenomenon, it will come," he said.
"But what we can do is to limit its impact."
He said a contingency plan was being released on Thursday, outlining the steps the government would take in the event of an outbreak.
750,000 deaths?
If a new strain did hit the UK before a vaccine was created, Sir Liam said an extra 50,000 would probably die - and a death toll of 750,000 was "not impossible".
"In a normal winter flu year... flu actually kills in excess of 12,000 people," Sir Liam said.
"But if we had a pandemic, the problem would be that our existing vaccines don't work against it, we would have to develop a new vaccine, and people don't have natural immunity because it hasn't be around before."
The total death toll depended on whether the mutated strain was a mild or
serious one, he said.
If a pandemic did materialise, the top priority other than vaccination would
be anti-viral medicine which would "stop some people dying", Sir
Liam said.
The UK has ordered 14.6m doses of anti-viral drug Tamiflu - enough for 25% of the population - which would alleviate symptoms among people affected.
Sir Liam admitted the UK only had 2.5m doses so far, with 800,000 new doses arriving every month.
The chief medical officer said key NHS workers would be the first to get treatment, but during any outbreak it would soon become apparent which age group was worst affected, and treatment would be targeted towards them.
Measures such as controlling movement of populations were not so important, because flu transmitted extremely quickly, he said.
However, the government might advise people to avoid non-essential travel in a bid to slow the spread of the virus, he acknowledged. It also might prove necessary to close schools and other public buildings.
But this would not affect air travel, he said.
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