Mia is 5 years old and bought in by her father after he observed a red rash on her cheeks this morning. Over the last two days she has had a runny nose and has complained of feeling achey. There is no rash elsewhere and she has been eating and drinking as normal. Observations today are normal, and examination of the chest, ears and throat is unremarkable. You note the erythematous rash on her cheeks.
Based on the likely diagnosis, which one of the following statements about the condition is least correct?