2.1 Randomisation To avoid contamination, a clustered randomised study design was chosen. Each cluster is made up of one practice. A minimum condition to participate as a practice is being able to recruit 36 children during 1 year. A first randomisation procedure will create 2 groups: CRP point of care test or no testing. A second randomisation procedure will create 2 more groups: brief intervention and parent information leaflet or no communication-intervention.