lu levels are continuing to rise in England, amid warnings that vaccine take-up among young children and pregnant women remain below that in previous years.
Infection rates are estimated to be highest among five to 14-year-olds, with 18.5% of laboratory samples from this age group testing positive, according to the UK Health Security Agency (UKHSA).
Some 10.5% of samples from all age groups tested positive in the week to November 27, up from 8.5% the previous week.
Hospital admission rates are highest for children under five and adults aged 85 and over, at 6.9 per 100,000 people.
Overall levels of flu are still estimated to be below where they were this point three years ago, in the pre-Covid winter of 2019/20.
But vaccine uptake among pregnant women currently stands at 29.3%, down five percentage points on this stage last year, and around three points lower than in 2020/21.
Uptake among two and three-year-olds is more than nine percentage points lower than last year and just over 14 points below the equivalent level in 2020/21.
Around a third (33.2%) of two-year-olds have now received a flu vaccine, along with just over a third (35.4%) of three-year-olds.
All children aged two and three are eligible for a flu nasal spray vaccine, which is being offered by local GPs.
In total around 33 million people in England can get a free flu vaccine this year, including everyone aged 50 and over, all primary-age children and some secondary-age children.
The vaccine is also being offered to pregnant women, people in care homes, frontline health and social care staff, carers, those aged six to 49 with a specified health condition, and household contacts of people with weakened immune systems.
Dr Conall Watson, UKHSA consultant epidemiologist, said: “Flu vaccine uptake among pregnant women and young children is low for this time of year. This is concerning given the expected reduced levels of natural immunity across the population following two winters with little flu.
“Getting the vaccine when you are pregnant can protect you and your baby against potentially serious complications.
“It can take a couple of weeks to build up full immunity after the vaccine, so it is important to book yours as soon as possible to get protected in time for the festive season.”
Separate figures from NHS England show there were an average of 482 flu cases per day in hospitals last week, up 40% from 344 the previous week.
Adult norovirus cases have also increased, accounting for an average of 157 beds per day last week, up 25% from 126.