The virus (Respiratory syncytial virus) usually causes cold-like symptoms but can give more serious respiratory infections in some cases.

“The increase in respiratory symptoms is being seen particularly in children and adults up to their forties, which fits well with the trend of children and their parents getting sick,” NIPH’s senior medical consultant Margrethe Greve-Isdahl said in a statement.

Although a seasonal increase in cases of the RSV is normal, it has begun earlier in the autumn than usual, according to NIPH.

The trend, which has also been observed in neighbouring Sweden and Denmark, has been linked to lower immunity in the population because social distancing measures taken against Covid-19 in 2020 also reduced the spread of other seasonal infections.

Outbreaks of RSV are usually most common between November and May.

Most adults and children usually experience the virus as a cold-like illness. In some cases, however, a more serious infection can persist in the respiratory system.

Infants under the age of 1 year can risk developing bronchiolitis, a blockage of small airways in the lungs which can require hospitalisation.

Between 1,000 and 2,000 children aged 0-5 are hospitalised with RSV in Norway each year, according to NIPH.

“In recent weeks we’ve seen an increase in confirmed cases of several different respiratory viruses alongside increased respiratory symptoms in the population,” Greve-Isdahl said.

How does the virus present in children if symptoms become serious?

Bronchiolitis can cause coughing fits and breathlessness and can particularly affect infants but also children up to the age of five. Symptoms often begin as a cold and develop over a few days. The virus can cause a loss of appetite in children. Breastfeeding mothers may notice a buildup of milk, NIPH writes.

“If you are concerned about your poorly child, it’s important to contact the health service. Children who are struggling to breathe should be seen by a doctor. Generally, the threshold for contacting a doctor should be lower the younger the child is,” Greve-Isdahl said.

What can parents do?

NIPH recommends parents keep children with new cold-like symptoms home from school, nursery or kindergarten, because respiratory infections are most easily transmitted during the first few days of illness.

Children can return to school or daycare once they no longer have a fever and most symptoms are receding, and the child feels themselves again. It’s okay for children to still have a runny nose, for example, if their symptoms have otherwise returned to normal.

The health authority also recommends avoiding visits to families with infants or women in the late stages of pregnancy if you have any cold-like symptoms.