In the UK, the total number of confirmed cases identified stands at 1,320.
England's chief medical officer Sir Liam Donaldson said swine flu presented a slightly higher risk to those with existing respiratory illness, asthma, cardiovascular disease and to pregnant women, but was also hitting healthy young adults.
He said people needed to remain vigilant and to follow good basic hygiene practices including using and disposing of tissues for coughs and sneezes and regularly washing hands with soap.
Virologist Professor John Oxford said that despite the death, the public should not panic.
"I still think the chances of picking up the virus are remote. It is not going to get any worse during the summer," he said.
He later told the BBC that although there was expected to be a rise in the number of cases in the autumn, measures were already in place.
"Britain is the most prepared country in the world," he said.
Professor Hugh Pennington, a bacteriologist at Aberdeen University, said the death was sad but was "to be expected".
"It does not point to the virus getting nastier. All the evidence to date suggests the virus is not changing at all.
"This is a flu virus, it is in no way different from an ordinary winter flu virus, so if there are enough cases some people will have to be admitted to hospital and some will die."
He added that the existence of underlying health problems meant it was "more likely" a patient would get the serious form of the virus.
Professor Peter Openshaw, a flu expert at Imperial College London, said about one in every three people infected would not even be aware that they had swine flu because they would have no or only very mild symptoms.
"And about 98% of people who get infected will recover fully without any hospital treatment so I think the public needs to be reassured," he said.
In the UK, the government now accepts that what it terms "sustained community transmission" is now taking place.
This is characterised by an increased number of sporadic cases with no identifiable link with other confirmed cases
The government estimates that the UK has enough anti-viral drugs for 50% of the population but has plans to raise that figure to 80%.
Ministers urged people not to alter their normal behaviour and follow hand hygiene guidelines.
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