Parents were yesterday urged to remain vigilant to the threat of flu ahead of an expected rise in new cases of the virus as children return to school following the Christmas holidays.
Health experts also stressed that it was not too late for members of "at risk" groups, including those with chronic respiratory problems, to be vaccinated against flu, which has been linked to 39 deaths in Britain since October.
Professor John Oxford, an expert in virology at St Bartholomew's and the Royal London Hospital, said the return of children to school had in the past prompted a rise in the number of flu cases.
"You tend to get a surge," the professor said. "I would anticipate a surge, but how long that will last is difficult to say."
Recommending that parents of children in high-risk groups should have them vaccinated as soon as possible, Prof Oxford added: "This virus is not going to go away next week. Even if it's already peaked, it's still going to be around for the next couple of weeks and it's still worthwhile being vaccinated at this stage."
Parents had no need to panic but should adopt a disciplined approach to curbing the spread of flu, said the expert, who advised them to keep children away from school if they showed signs of flu.
Although closing schools in response to flu pandemics had not proved effective, Prof Oxford said parents could aid the fight against the virus by ensuring good hand hygiene and keeping children away from others with the illness where possible.
Dr Douglas Fleming, director of the Royal College of General Practitioners' Research and Surveillance Centre, also voiced concern that the current flu outbreak may not have peaked despite the fact that a large number of children had already had the virus.
"This is a H1 virus and we know that spreads rapidly amongst children," Dr Fleming noted. "I personally don't feel that we have quite reached the peak."
The Government relaunched its national flu prevention campaign on New Year's Day. Health Secretary Andrew Lansley ordered the reinstatement after it was confirmed that the number of people in critical care with confirmed or suspected flu in England has risen to 738, including 42 youngsters under five.
Government advisers from the Joint Committee on Vaccination and Immunisation (JCVI) are also continuing to urge the vulnerable to be vaccinated against the virus.
The Health Protection Agency (HPA) said last week that the vast majority of the 39 people to die since October had been diagnosed as having the 2009 strain of swine flu.
HPA officials said that although many people reported relatively mild symptoms during the pandemic, flu could be an extremely serious illness for people in "at risk" groups, including pregnant women, the elderly and those with other underlying conditions.