RSV: Warning of post-Covid ‘immunity debt’ as babies are hospitalised with childhood virus usually seen in winter

RSV, which typically spikes during the winter months, can cause severe illness in children five years and younger

Health experts have reported seeing an increased number of young children and babies contracting a respiratory illness, as they warn the uptick could be due to coronavirus restrictions lifting.

The Centers for Disease Control and Prevention released a health advisory last month warning about the increase of children contracting respiratory syncytial virus (RSV).

RSV, which typically spikes during the winter months, can cause severe illness in children five years and younger and older adults.

Dr Claudette Poole, a paediatric infectious diseases physician at Children’s of Alabama, told NBC News that the virus was likely “making up” from the winter season, which was when most of the country was under stricter coronavirus restrictions.

“My speculation is that because we suppressed its normal circulation time during the winter, it’s sort of making up for lost time now,” Dr Poole said.

In most cases with RSV, the virus just causes mild symptoms similar to the common cold. But it can develop into severe bronchitis and pneumonia in young children and the elderly. Typically it kills about 500 children under the age of five each year.

RSV activity remained low between May 2020 and March 2021, but the CDC has reported that there has since been an uptick in cases since late March, according to the National Respiratory and Enteric Virus Surveillance System (NREVSS), a laboratory-based surveillance network.

Health experts said reduced circulation of RSV during the winter season might mean that infants and toddlers could have an increased risk of severe RSV symptoms since they did not experience normal levels of exposure to the virus compared to past seasons – referring to it as an “immunity debt”.

An immunity debt can happen when people who have not been exposed to normal levels of viruses and bacterias experience a surge in infections when coming in contact with a virus.

“There weren’t as many children in daycare because many parents were out of work or working from home,” Dr Sean McTigue, interim chief of the division of paediatric infectious diseases at University of Kentucky HealthCare, told NBC News.

The respiratory illness, like Covid-19, can spread through droplets in the air when someone coughs or sneezes.

The United States is not the only country experiencing a spike in RSV cases. New Zealand has also reported an increase in children falling ill with the respiratory virus.

The country has reported nearly 1,000 RSV cases in the past five weeks, according to the Institute of Environmental Science and Research.

In infants younger than six months, RSV can cause symptoms like irritability, poor feeding, and apnea. Older infants and young children can experience a decreased appetite before having a cough, fever, and wheezing.

In the health advisory, the CDC said the RSV spike deviated from a typical circulation pattern for the virus, so it was not possible for the agency to anticipate the spread, peak, or duration of viral activity.

Health experts have advised parents to closely monitor their children if they have an underlying health conditions given the current RSV spike.

Parents could also choose for their children to wear masks once school starts in the fall as an added barrier to protect against viruses like RSV.