Update: - Let's beware of complacency folks...
President Barack Obama has warned that the US is not "out of the woods yet" in containing a swine flu outbreak.
He said the virus was not as virulent as first feared, but warned of the possibility of "an even worse flu season sometime in the fall [autumn]".
Earlier, officials said the number of confirmed infections in the US had nearly doubled overnight to 1,639.
Meanwhile, Canada reported its first confirmed flu death in the western Alberta province.
And people are being more careful, which is helping:
The good news is the publicity surrounding the outbreaks has made people change their behavior, Besser said.
Dr. Robert Blendon and colleagues at the Harvard School of Public Health surveyed 1,000 U.S. adults, including people who only have cellphones -- a first for a major public health survey.
They said 67 percent reported they or someone in their household has washed their hands or used hand sanitizer more frequently because of the outbreak. And 55 percent had made plans to stay home with children or work from home if they became sick, if school closed or if a family member got sick.
"This has really gotten into their lives," Blendon told the briefing. "This is not something people are watching and not doing anything about. It is quite incredible."
Besser said H1N1 presented a "teachable moment" that could not only help people better prepare for future pandemics but change the course of other infectious diseases.
"If they can make handwashing something that is routine, if they can make covering their coughs appropriately something that is routine ... they will protect themselves not only from influenza but so many respiratory infections," Besser said.
"It would be absolutely wonderful if a spin-off from people taking more precautions against flu would be a decrease in gastrointestinal diseases."
Outbreaks of the new H1N1 swine flu continue to spread across the United States, with 896 confirmed cases and more to come, the U.S. Centers for Disease Control and Prevention reported on Thursday.
U.S. officials have said they expect the swine influenza virus to spread to all 50 states and to cause many infections ranging from mild to severe.
Acting CDC Director Dr Richard Besser said the actual numbers matter less than the pattern of disease. "So far we are not seeing any signs of this petering out," Besser told reporters. "We are on the upswing."
It could effect a large number of people worldwide:
Up to 2 billion people could be infected by swine flu if the current outbreak turns into a pandemic lasting two years, the World Health Organization said Thursday.
WHO flu chief Keiji Fukuda said the historical record of flu pandemics indicates one-third of the world's population gets infected in such outbreaks. Independent experts agreed that the estimate was possible.
John Oxford, professor of virology at St. Bart's and Royal London Hospital:
"I don't think the 2 billion figure should scare people because it's not as though 2 billion people are going to die. The prediction from WHO is that 2 billion people might catch it. Half of those people won't show any symptoms. Or if they show any symptoms, they will be so mild they will hardly know they've had it."
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