This page explains that the child in your care has had a successful allergen challenge. This means they are not allergic to that item and it can be safely introduced into their diet.
Most allergic reactions happen immediately after the allergen has been eaten or contact made with the allergen e.g. latex, medication, and almost always happen within an hour. The child has been observed on the ward for at least 2 hours without any evidence of a reaction. It is now safe for the child in your care to go home. Delayed reactions can happen but this is extremely unlikely.