Health officials have changed the flu vaccination over fears a deadly strain from Australia, called Brisbane H3N2, could arrive in Britain.
The virus has already claimed the lives of scores of children in Australia. It affects three times the number of victims hit by other strains, with many deaths resulting from pneumonia.
The flu strain is so virulent that health chiefs have had to change the make-up of the flu vaccine to deal with it.
Between June and July 2007 in New South Wales, there were more than 800 deaths from pneumonia, many of them children.
It is common for viruses to head up from the southern hemisphere in the winter but experts say we are at greater risk this year.
"If the seasonal flu is as bad as it was in Australia, you are in for a torrid time," the Daily Star quoted inventor of the flu vaccine, Dr Graeme Laver, as warning Britain.
Fever, tiredness, dry cough, sore throat, nasal congestion and an aching body are among the symptoms.
Hugh Pennington, a professor at Aberdeen University, said: "If this flu has been busy in Australia, it is reasonable to suppose we may get a similar situation in the UK.
"Viruses travel round the world very quickly now. We have had some very quiet flu years recently and every year we have to assume that it will be busier. There is no doubt elderly people are most at risk," Pennington added.