More people in the UK died after contracting swine flu last winter than during the previous year's pandemic, according to new figures.
The Health Protection Agency (HPA) said 602 people in the UK were reported to the agency as having died with a confirmed flu infection during the 2010/11 season.
Where information was available on the strain of the infection, more than 90% of these deaths - 535 out of 582 - were influenza A H1N1 swine flu, while influenza B was associated with 40 deaths, the agency said in its annual flu report.
The figures for this winter compare to 474 deaths reported between June 2009 and April last year as being associated with the H1N1 swine flu.
The agency said young and middle-aged adults bore the brunt of influenza this winter, with more than 70% of fatal cases in this age group.
In England, just 50% of adults under 65 who were in an "at risk" group and eligible for flu vaccination last season received the vaccine, down slightly from the 2009/10 season.
Among over-65s in England - all of whom are offered vaccination - 73% accepted, up slightly from the previous year.
Just 37% of healthy pregnant women in England were vaccinated, while among expectant mothers with underlying conditions, the figure was 57%, the agency said.
Professor John Watson, head of the respiratory diseases department at the HPA, said the annual flu report showed that seasonal flu activity in 2010/11 was higher than last winter and the H1N1 swine flu was the dominant strain.
"For the majority of people with these conditions, flu is a preventable illness and ahead of the next flu season, a concerted effort must be made by healthcare professionals - including GPs and midwives - to encourage those at risk to take up the offer of vaccination. It is the best way to protect against flu," he said.