Young children frequently attend the emergency department (ED) with wheeze which is usually triggered by a virus infection, such as the common cold. Wheeze can be treated with inhaled medications and sometimes oral steroid medicines are also given to reduce swelling within the lungs. Unfortunately, oral steroids can have side effects. Despite lots of research there is no clear evidence that oral steroids work in young children with a wheeze attack. It is likely that some children get better quicker with oral steroids but deciding who to treat is difficult. This results in differences in care with some children receiving unnecessary oral steroids and others not receiving them when they could benefit. The investigators hypothesise that in a subgroup of children with mild-to-moderate acute wheeze attacks, the viral trigger can predict their response to steroid medications. Previously, respiratory virus testing was too slow to be used to inform treatments in the ED. Now, point-of-care (POC) viral tests can provide results within 30 minutes. There is a research gap regarding the role of these tests in determining steroid responsiveness and outcomes in children presenting with acute wheeze in the pre-school population. In order to address the hypothesis in a future definitive trial, the feasibility of using (POC) viral tests to randomise steroid treatments for children in a clinical study in the ED setting must be ascertained. The PRECISE Study will therefore be a single centre randomised, feasibility study enrolling approximately 60 pre-school aged children to inform a future definitive multi-centre Randomised Controlled Trial.