Around 1,000 children have already needed hospital care, the British Lung Foundation said.
Parents of young children have been urged to be alert for signs of a common winter illness in children after a charity warned that there could be a surge in cases.
The British Lung Foundation (BLF) said that respiratory syncytial virus (RSV) is ”rife” due to lowered immunity in the population.
Cases of the condition usually peak in January, but there were few infections last year when there were lockdowns in place.
The charity said it was concerned that this year children will have “much lower immunity” at a time when the NHS is already under extreme pressure.
It said that a surge in cases this year could coincide with large numbers of Covid-19 infections.
The BLF has already seen a 400% rise in calls to its helpline from parents worried about their child having breathing difficulties.
RSV is common in babies and children, and almost all children will have had it by the time they are two years old.
The virus may cause a cough or cold. But for some, it can lead to bronchiolitis – an inflammatory infection of the lower airways which can make it hard to breathe.
RSV is a common virus causing colds and coughs but can be more severe in some children. Find out more about the symptoms and what to do if you’re concerned here https://t.co/2fGAoMnXlW pic.twitter.com/5k8FePa33x
— NHS Coventry and Warwickshire CCG (@CWCCG) January 10, 2022
The early symptoms of bronchiolitis are similar to those of a common cold but can develop over a few days into a high temperature, a dry and persistent cough, difficulty feeding, and wheezing.
While many cases clear up in two to three weeks, a number of children need hospital admission.
The BLF said that over the past three months an estimated 1,000 children have needed hospital care in England alone.
It has issued new guidance for parents which includes asking anyone who has a cough or cold to stay away from young children, making sure that anyone who handles their child washes their hands regularly and not smoking around young children and babies.
Respiratory infections in young children are rising. RSV is a common virus causing colds and coughs but can be more severe in some children.
Contact your GP or 111 if you're worried about your child.
— NHS Nottingham and Nottinghamshire CCG (@NHSNottsCCG) January 10, 2022
Dr Andy Whittamore, clinical lead at the British Lung Foundation, said: “In general practice, we are seeing a lot of children with coughs and viruses that weren’t circulating last year and so their immunity is lowered.
“Doctors on the ground are concerned that alongside a rapid increase in cases of Covid-19, we are also going to see a surge in diseases like bronchiolitis.
“Like most other colds and viruses, RSV starts with a blocked or runny nose and can progress to cause a cough, fever and sometimes breathing difficulties. The good news is that for most children it will be mild and will clear in a few days without any treatment. Sometimes a cough might drag on for a few weeks.
“It is extremely rare for a well child to die of bronchiolitis, but there are some who will need medical help, although that is still unusual. Some babies do develop severe symptoms with the RSV virus, and warning signs to look out for include if they refuse to feed, are becoming very breathless or if they are breathing in a shallow or irregular way.
“We would advise any parents worried about their child having RSV to speak to their doctor or call our helpline on 03000 030 555. Parents can also visit the British Lung Foundation website.”