Randomisation
PCT
Participants will be randomised in a 1:1 ratio to receive either current clinical management alone (control) or clinical management with the addition of PCT test guidance (intervention). Patients will be randomised by minimisation [Participants will be randomised remotely using a secure 24-h web-based randomisation programme controlled centrally by the Centre for Trials Research at Cardiff University. Details of the age group cut-offs and random element are documented in a separate randomisation protocol and will be concealed from the treating teams.