Britain could have more than 100,000 cases of swine flu a day by the end of August, the government said Thursday, while stressing there was no need for alarm.
Health Secretary Andy Burnham said the figures could occur if current trends of infection continued in Britain, where the number of cases of the A(H1N1) virus is doubling every week and has reached nearly 7,500.
"Cases are doubling every week, and on this trend we could see over 100,000 cases a day by the end of August, but I stress this is only a projection," Burnham told the House of Commons, the lower house of parliament.
"This situation may change and of course we must always plan for the more difficult circumstances," he later told reporters.
The rising number of cases has forced health officials to abandon a policy of trying to contain the virus, and will instead focus on treating infected people with antiviral drugs, with high-risk patients given priority.
Laboratory testing will no longer be conducted to confirm cases and drugs will not be given to close contacts of those infected unless they show symptoms.
"People should be reassured and should not be alarmed by this change (of dealing with the virus). But we must continue to treat the virus with the greatest of respect and proceed with caution at all times," Burnham said.
Three people have died in Britain after contracting the virus, which erupted in Mexico in late March before spreading around the world. All three had pre-existing health problems.
England's chief medical officer Liam Donaldson said the virus was not spreading out of control, and health authorities were continuing to fight it "very aggressively".
"It isn't out of control. It's following a predictable path," he said.
"But flu viruses whether they are seasonal or novel pandemic viruses like this cannot be controlled and put back in their box until you have an effective vaccine."
The first batches of swine flu vaccines were set to arrive in Britain in August, with 60 million doses available by the end of the year -- enough for half of the population, Burnham said, adding that more would follow.
Donaldson said it was unclear why the virus appeared to be spreading faster in Britain than elsewhere in Europe, suggesting large amounts of travel between Britain and North America, where case numbers are high, could be one reason.
"That's one factor but we can't be absolutely sure," Donaldson said.
The heavily populated West Midlands region in central England, which includes the city of Birmingham, is one of several declared hot spots.
Burnham suggested close family ties among large numbers of Asian and other families living there could be a reason for the higher number of cases.
People with swine-flu symptoms are being advised to contact health services or their doctor and stay at home. A friend or family member will be delegated to collect antivirals from pharmacies and other drug collection points.
The latest numbers from the World Health Organisation, released on Wednesday, showed 77,201 people reported swine flu cases worldwide, with 332 deaths.
Argentina has surpassed Canada as the country with the most swine flu-linked deaths after the United States and Mexico.
(c) 2009 AFP
Explore further: Middle East Respiratory Syndrome coronavirus detected in the air of a Saudi Arabian camel barn