Cases of flu rose by more than 40% last week according to figures from doctors.
The Royal College of General Practitioners (RCGP) reported that cases of flu in England and Wales reached 124.4 per 100,000 of the population in the week ending December 26.
There were 85.8 per 100,000 cases in the previous week.
A Department of Health spokesman said: "These figures are in keeping with what we would expect during a winter flu season.
"But everyone can do their bit to help keep well - simple measures like washing your hands help stop flu spreading.
"The Chief Medical Officer has issued clear advice to get the seasonal flu jab if you are in a vulnerable group, particularly pregnant women and people with an underlying health condition, as well as those aged 65 and over.
"We are pleased to hear from RCGP that their estimates show vaccine coverage in over 65s has now caught up with last year and coverage is still going up in under 65s' in-risk groups."