Dr Alex Allen, a consultant epidemiologist at UKHSA, urged all eligible people to come forward for vaccination.
Everyone aged 65 and over, pregnant women and those with certain long-term health conditions can get a free flu jab on the NHS.
“If you’re eligible for a vaccine it is because you are at greater risk of severe illness – every year we see many thousands end up in hospital and far too many deaths from flu.
“It’s crucial that everyone eligible books their appointment as soon as possible. The vaccine is our best defence.”
He also reminded parents of under 16-year-olds to return consent forms to school so their children can get vaccinated, or if they are aged two and three to arrange a vaccine via their GP.
“The nasal spray vaccine can help stop your child from getting very unwell and reduce the risk of passing flu to vulnerable family members.
“Anyone with flu or Covid symptoms – including high temperature, cough, and feeling tired or achy – should minimise contact with others, especially those who are vulnerable.
“If you need to go out with symptoms, consider wearing a face covering, wash hands regularly and ensure indoor spaces are well ventilated,” he added.
Meanwhile, UKHSA said Covid cases were decreasing and the virus was now at baseline levels.