A medical chief has said there is no need for alarm despite a hospital patient becoming the first person without underlying health problems to die after contracting swine flu.
The patient died on Friday at Basildon and Thurrock University Hospitals NHS Foundation Trust, NHS East of England said - taking the total number of UK swine flu-related deaths to 15.
In the other 14 cases the people involved had underlying health issues, such as heart problems and long-term illnesses.
Professor Steve Field, chairman of the Royal College of General Practitioners, said the latest death should not lead to panic.
"This doesn't change things at the moment," he said. "We would expect a certain number of deaths. I would have expected a death with no underlying causes to have happened earlier. It doesn't change anything we're doing."
The patient's family has asked that no details of their relative be released.
Chief Medical Officer Sir Liam Donaldson said: "This death underlines that, although the virus is proving generally mild in most people, it is more severe in some cases.
"As with all flu-like viruses, some people are at higher risk than others. Unfortunately, people who are otherwise healthy could also become seriously ill or, sadly, die."
The Essex patient was the first in the UK with no underlying health problems to die after contracting swine flu but not the first in the world, the Department of Health said.
John Oxford, Professor of Virology at Queen Mary's College of Medicine in London, said the death was to be expected and did not give any extra cause for concern. The Essex patient may have died from the virus moving deep into their respiratory tract and into the lung, followed by an infection of the lungs by a bacterium, he added. This would result in breathing difficulties and pressure on the heart.