Viral URIs may be more difficult to identify in young children, who cannot articulate the presence of many symptoms. In our study, greater than 10% of parents indicated they could not tell whether their child had a headache or sore throat, both components of the Jackson score for defining a cold (8) . Furthermore, the diagnostic properties in patients in whom the Jackson score could be calculated were not as good as our URI symptom score. This confirms our assertion that the Jackson score is not appropriate for clinical trials in children, and a new symptom scoring system is needed to identify viral URIs in pediatric patients.