Health chiefs say a virus which can make it hard for some young children to breath is on the rise.

Parents are being encouraged to look out for the signs of respiratory illnesses in young children, as data from Public Health England (PHE) shows cases are starting to rise in some parts of the country.

Respiratory illnesses including colds and respiratory syncytial virus (RSV) are very common in young children, in fact almost all children are infected with RSV by the time they are two years old.

However, last winter, due to the lockdown, there were far fewer infections in younger people.

This means many children will not have developed immunity and so we may see more cases this year than in a typical season.

For the majority of children, these illnesses will not be serious and they will soon recover following rest and plenty of fluids.

In older children and adults, RSV may cause a cough or cold, but some children under the age of two, especially those born prematurely or with a heart condition, can suffer much more serious consequences from these common infections.

One of them is bronchiolitis, an inflammatory infection of the lower airways which can make it hard to breathe.

The early symptoms of bronchiolitis are similar to those of a common cold but can develop over a few days into a high temperature of 37.8°C or above (fever), a dry and persistent cough, difficulty feeding, rapid or noisy breathing (wheezing).

Most cases of bronchiolitis are not serious and clear up within two-to-three weeks, but you should contact your GP or call NHS 111 if:

- You are worried about your child.

- Your child has taken less than half their usual amount during the last two or three feeds, or they have had a dry nappy for 12 hours or more.

- Your child has a persistent high temperature of 37.8C or above.

- Your child seems very tired or irritable.

Dial 999 for an ambulance if:

- Your baby is having difficulty breathing.

- Your baby's tongue or lips are blue.

- There are long pauses in your baby's breathing.

Dr Nikki Stevenson, executive medical director at Wirral University Teaching Hospital, said: "This winter, we expect levels of common seasonal illnesses such as cold and flu to increase as people mix more and because fewer people will have built up natural immunity during the lockdowns in the pandemic.

"Children under two are at a particular risk of severe infections from common seasonal illnesses.

"If a child under two is suffering from a cold, keep a close eye on their symptoms and make sure to contact your doctor if they get a high temperature, become breathless or have difficulty feeding.

"It's important that we carry on with good hygiene habits that we've become used to during the pandemic, in order to protect ourselves and those around us."

Ruth May, chief nursing officer for England, said: "For most children these illnesses won't be serious and they will soon bounce back, but if you do need medical help for your child, especially if they are under two, please do come forward for the care you need.

"The NHS has detailed plans in place for a wide range of scenarios ahead of winter and will continue to adapt them as needed, in line with the guidance from Public Health England."

As part of the NHS response, the offer of the preventative medicine palivizumab has been brought forward from the usual October start date and the number of doses has been extended from five to seven.

The medicine will also be offered to young children who are at the highest risk of complications from RSV, reducing the risk of hospitalisation in those most vulnerable.

This follows advice from the Joint Committee on Vaccination and Immunisation (JCVI).