Health chiefs have urged people to take up the flu vaccine after it emerged that the swine flu virus which swept the country last year has claimed the lives of 10 adults in the UK in the past six weeks.
The Health Protection Agency (HPA) confirmed that the deaths were in younger adults under 65 and associated with H1N1 swine flu.
Most had underlying conditions but "a small proportion" were healthy before contracting the virus, a spokeswoman said.
The deaths came against a background of a low rate of doctor visits. GP consultations for flu-like illness in England were 13.3 per 100,000 population last week.
Professor John Watson, head of respiratory diseases department at the HPA, said: "Over the last few weeks we have seen a rise in the number of cases of seasonal flu, including both H1N1 (2009) and flu B, in the community. We have also received reports of patients with serious illness requiring hospitalisation and outbreaks of flu in schools across the country.
"For most people, flu is not life threatening and usually lasts seven to 10 days. However, it can be far more dangerous for those in at-risk groups, such as the elderly, pregnant women and patients with heart problems, diabetes or lung, liver or renal diseases, or those who have weak immune systems who are at risk of developing complications.
"Flu vaccination offers the best protection for those at high risk from seasonal influenza. If you are in an at-risk group and you haven't had your jab, we recommend you make an appointment with your GP or medical practitioner now.
"Although unpleasant, flu is a self-limiting illness and if you have flu it is best to stay at home until well. If individuals in at-risk groups develop symptoms consistent with flu or if anyone whose symptoms persist or become more severe then we advise they seek medical advice."
Professor David Salisbury, director of immunisation at the Department of Health, said: "These figures demonstrate that the effects of flu are not to be underestimated. It is not the same as getting a cold and can seriously affect your health.
"The seasonal flu jab protects against the dominant strains - this year it protects against three types of flu, including the type known as swine flu."
