Britain faces a projected 100,000 new swine flu cases a day by the end of August and must revamp its flu strategy to cope, the nation's health minister said Thursday.
Britain has officially reported 7,447 swine flu cases and three deaths, but officials acknowledge the real number of cases is far higher, since many with the virus have not been tested.
Britain is the hardest-hit nation in Europe amid the global swine flu epidemic. Many flu experts believe numbers could jump exponentially now that the virus is entrenched. Because swine flu, or H1N1, is a new virus, few people have any natural immunity, allowing the virus to spread rapidly.
"Cases are doubling every week and on this trend we could see over 100,000 cases per day by the end of August," Health Minister Andy Burnham told the House of Commons on Thursday.
Britain has been reporting several hundred new swine flu cases daily for the last several weeks. If that surges to 100,000 cases a day by the end of August, there could be 6 million people infected by the fall, or 10 percent of Britain's 60 million population.
Since flu spreads more quickly in densely populated areas, cases in Britain will probably be concentrated in cities like London,
Birmingham and Manchester.
Other experts wondered how Burnham came up with the 100,000 prediction. "I don't know how they got that figure," said John Oxford, a professor of virology at St. Bart's and Royal London Hospital. "It seems like a lot of mathematical modeling and not too much common sense."
Oxford predicted swine flu would taper off with the warm weather in summer, when flu viruses usually disappear, before returning in the regular flu season in the winter. He said no one could accurately predict how many cases there might be and that all numbers were just guesses.
Britain had been trying to contain the disease by liberally giving out the drug Tamiflu to all suspected swine flu cases and their contacts. Yet many experts have criticized Britain's attempt to contain the outbreak, saying it wastes resources, drugs and could promote antiviral resistance.
Burnham said Britain will now only give the antiviral to people believed to have the virus.
The World Health Organization has said that 2 billion people could eventually be infected with swine flu worldwide. Most cases are mild and require no medical treatment. More than 77,000 cases, including 332 deaths, have been reported worldwide.
Other countries including Australia, Japan and the United States, initially tried to contain swine flu by giving out Tamiflu widely, but dumped the strategy within weeks.
Still, Britain's top medical officer defended the country's earlier approach.
"We've been fighting this pandemic very aggressively," Sir Liam Donaldson said during a press conference. "We're unapologetic about that."
Donaldson said Britain probably had the world's largest stockpile of Tamiflu. The antiviral can alleviate swine flu symptoms and shorten the course of illness by about a day if patients take it within 48 hours of getting sick.
Earlier this week, health officials reported the first instance of Tamiflu resistance, in a Danish patient who had been taking the drug. Experts worry that if Tamiflu is given out widely - as per Britain's earlier approach - that could make it easier for the virus to develop resistance.
Burnham said people with swine flu symptoms should check health services websites or call flu hotlines to get help before seeing their doctors. He said patients should stay at home and have friends pick up drugs for them from designated community centers.
The sharp jump in Britain's numbers may also reflect the country's previous refusal to look for the disease. When swine flu arrived in the U.K., officials only tested people who had traveled to North America, where the epidemic began, or those in contact with a confirmed swine flu case.
That meant the testing system did not pick up the virus' spread into communities.
WHO's declaration in June that swine flu was a pandemic - a global epidemic - was made partly because the agency felt some countries, including Britain, were not accurately reporting their swine flu outbreaks.
Burnham also predicted the first doses of swine flu vaccine would arrive in Britain in August. Britain has ordered 60 million doses of vaccine, enough to cover the entire population.
Other experts, however, doubt the vaccine will be available that quickly, since it needs to be produced, tested in humans and meet regulatory approval - a process that may take longer than two months.
Regular flu kills up to 500,000 people a year worldwide, but scientists said just because swine flu is spreading faster does not mean it is getting any more lethal.
"No one is predicting this will be more deadly, just that there will be more of it," Oxford said.