By Pallab Ghosh
BBC News science correspondent
The UK government has been too slow in formulating plans to combat a potentially lethal flu pandemic, a leading expert has warned.
The team quizzed nearly 46,000 people in Vietnam
Professor Neil Ferguson, of Imperial College London, said there were no clear plans for ensuring rapid access to vaccines and drugs.
Professor Ferguson's work, published in Nature, suggests early treatment could halve the number falling ill.
The Department of Health has dismissed the concerns.
The department pledged to assess the cost and benefit of Professor Ferguson's recommendations when his preliminary findings were released last December.
He recommends that the department doubles its stockpile of anti-viral drugs, and makes vaccination of children a priority.
His calculations show drugs need to be delivered to patients - and those living with them - within 24 hours to slow the spread of disease among the general population.
That strategy, known as household prophylaxis, could reduce the number becoming ill - and potentially dying - by a half.
But at the height of a pandemic that would mean delivering more than one million courses of drug each day.
According to Professor Ferguson, the Department of Health is not geared up to do that - and has done little to develop a capability since he expressed his concerns to BBC News last year.
He said: "We are significantly ahead of the curve in terms of getting stockpiles in place - which is excellent, we need the stockpiles in order to be able to respond.
"But we are perhaps behind the curve in terms of having plans to really use those stockpiles in a crisis."
England's Chief Medical Officer, Sir Liam Donaldson, said the government's pandemic flu strategy was based on expert advice from the Department's Scientific Advisory Group.
He said: "A strategy of household prophylaxis will be considered alongside other possible measures.
"We will continue to work with Professor Ferguson to explore other options that could protect the public."
Professor Ferguson has called for the creation of mobile units to deliver drugs to people's homes - because it would not be possible or sensible for people to go to their GP in the usual way.
He has also called for training exercises that would simulate the outbreak of a pandemic.
However, his study shows that it would not be worth closing borders in the event of a pandemic in another country.
The Department of Health is developing exercises and a strategy on the best way to deliver drugs
But Professor Ferguson is concerned that front line doctors have not been told about the plans, and that the project has not received sufficient funds.
The Department of Health argues stockpiling a vaccine is of limited value, as there is no guarantee it would be effective against a new pandemic strain.
But Professor Ferguson said his calculations suggested that even use of an imperfect vaccine could reduce tranmission in the general population by as much as a third.
His assessment is based on a mathematical model that simulates the spread of an average flu virus.
Experts fear a pandemic could result if a particularly deadly form of bird flu, H5N1, mutates so it can easily spread from person to person.