Officials called for GPs to use antiviral medicines to protect vulnerable patients against flu complications after HPA figures published on Thursday revealed a steep rise in cases.
Figures show there was a 50% rise in GP consultations for flu among children aged 5-14 last week, reaching 46.9 per 100,000. Flu consultations among the general population rose by 64%, from 14.3 to 23.4 per 100,000.
Outbreaks have been reported in certain schools and flu-related calls to NHS Direct have risen.
Dr Richard Pebody, head of seasonal flu surveillance at the HPA, said: 'We are seeing an increase in flu activity mainly among school children indicating the start of this year’s flu season.'
He urged at-risk patients to get vaccinated, adding: 'As levels of flu have started to increase, the HPA has recommended that antivirals should be used for the treatment and prevention of flu in those who are at risk of serious complications.'