Babies hospitalised with a severe respiratory illness before the age of two are twice as likely to develop childhood asthma, a large study has found.
Almost all Australian children will have Respiratory Syncytial Viral disease (RSV) before they turn three, but it can be more serious and require hospitalisation.
A study of all children born in NSW between 2000 and 2010, published in journal BMJ Open, found the risk of developing asthma was double that among the children hospitalised for RSV before their second birthday compared to children who were not hospitalised for RSV.
Those at greatest risk of developing asthma were babies born preterm and indigenous children, said lead investigator Nusrat Homaira from UNSW.
"In a previous study, we have already shown that the risk of developing severe RSV bronchiolitis, compared to otherwise healthy children, is 10 times more for children who are born preterm and two times more for indigenous children," Dr Nusrat said.
Australia has a high prevalence of pediatric asthma compared to other developed countries.
In 2014, more than 13,000 children aged 1-17 presented to NSW emergency departments with asthma - two thirds of all hospital presentations for this age group.
Dr Nusrat says there are several vaccines for RSV being tested in clinical trials but says the most important thing parents can do to protect their child is quit smoking.
"Parents should be aware that smoking is one of the strongest modifiable risk factors for developing severe RSV bronchiolitis for all children," Dr Nusrat said.