Swine flu 'to infect one-third of world'

Swine flu is likely to spread around the world in the next few months and infect one-third of the global population, according to the first detailed analysis of the spread of the virus published by British scientists today.

The study by researchers at London’s Imperial College, published in the journal Science, found that swine flu has “full pandemic potential”, spreading easily from person to person and infecting around one in three of those who come into contact with it.

But the research’s author, Professor Neil Ferguson, said it was too early to say whether the virus will cause deaths on a massive scale, or prove little more lethal than normal seasonal flu.

Its full impact is not likely to be known until the annual flu season in the autumn and winter, when a “really major epidemic” can be expected in the northern hemisphere.

Swine flu is certainly milder than the Spanish flu which caused an estimated 50 million deaths in 1918, but it is not yet possible to say whether it will kill more than the most recent pandemics in 1957 and 1968, he said.

Prof Ferguson, who sits on the World Health Organisation’s emergency committee for the outbreak, said the international community should decide this week whether to switch vaccine-production capacity away from seasonal flu to concentrate on swine flu.

He told the BBC: “This virus really does have full pandemic potential. It is likely to spread around the world in the next six to nine months and when it does so it will affect about one-third of the world’s population.

“To put that into context, normal seasonal flu every year probably affects around 10% of the world’s population every year, so we are heading for a flu season which is perhaps three times worse than usual – not allowing for whether this virus is more severe than normal seasonal flu viruses.”