Health officials are growing increasingly concerned about the low numbers of toddlers getting a flu vaccine as hospital admissions for complications caused by the virus leap by more than 70% among children under five.

Between November 14 and November 20 more than 200 youngsters aged just five and under had to be hospitalised suffering from serious complications connected to flu, says the UK Health Protection Agency.

Overall hospital numbers have grown by more than 70% in the last week, with increasing numbers of very small children suffering from flu needing to seek medical treatment because they are seriously unwell.

But the same time, the proportion of children aged two and three taking up the offer of a flu immunisation - via a nasal spray - has also dropped by around 11% when compared with the last two years.

With flu now circulating at higher levels than other recent winter seasons - encouraged by people's lack of natural immunity lost during lockdown and as a result of social distancing - health teams are worried about how vulnerable very young children now are to the virus.

Their risk, says the UKHSA, of becoming very poorly is elevated because so many pre-schoolers who lived their early years through the pandemic haven't ever encountered such a virus to develop any immunity of their own.

Flu symptoms can include a sudden high temperature, sickness, a sore throat, aching body, difficulty sleeping, dry cough, headache and stomach pain.

GP surgeries are inviting all children aged two and three for the nasal spray vaccination at practices and any family yet to hear from their doctor should contact them directly to make an appointment.

All primary school children and some secondary school year groups are also eligible for the flu nasal spray this year, which is mostly being given by community health teams within schools.

Dr Conall Watson, Consultant Epidemiologist at UKHSA, explained: "Young children are particularly vulnerable to becoming very poorly from flu. For the third week running we have seen hospitalisation rates among children under five jump up, with a 70% increase in just the last week. Over 200 children were hospitalised because of flu in one week.

"Flu is now circulating at higher levels than recent years and because of the pandemic restrictions most young children will not have encountered flu before. This means they will have no natural immunity and are therefore at even greater risk this year.

"Two and 3 year olds can get protection with a free nasal spray vaccine from the NHS. Nobody wants their child to get sick so I strongly urge parents to book the vaccine at their GP surgery as soon as possible."