Table 1

Eligibility criteria

  • Male or female, aged at least 1 year

  • Presenting with ILI in primary care during a period of increased influenza activity.

    • ILI=sudden onset of self-reported fever, with at least one respiratory symptom (cough, sore throat, running or congested nose) and one systemic symptom (headache, muscle ache, sweats or chills or tiredness), with symptom duration of 72 hours or less

  • Is able and willing to comply with all trial requirements

  • Participant or legal guardian(s) of a child is willing and able to give informed consent

  • Agrees not to take antiviral agents apart from study antiviral agents according to patient randomisation

  • Chronic renal failure, for example, known or estimated creatinine glomerular filtration rate <60 mL/min (known=recorded in participant’s clinical records)

  • Condition or treatment associated with significant impaired immunity (eg, long-term oral steroids, chemotherapy or immune disorder) (known=recorded in participant’s clinical records)

  • Those who in the opinion of the responsible clinician should be prescribed immediate antiviral treatment

  • Allergic to oseltamivir or any other trial medication

  • Scheduled elective surgery or other procedures requiring general anaesthesia during the subsequent 2 weeks

  • Participant with life expectancy estimate by a clinician to be less than 6 months

  • Patient with severe hepatic impairment

  • Responsible clinician considers urgent hospital admission is required

  • Any other significant disease or disorder which, in the opinion of the responsible clinician, may either put the participants at risk because of participation in the trial, may influence the result of the trial or may affect the participant’s ability to participate in the trial

  • Involvement, including completion of any follow-up procedures, in another clinical trial of an investigational medicinal product in the last 90 days

  • Previous Antivirals for influenza-Like Illness? An rCt of Clinical and Cost effectiveness in primary CarE trial participation

  • Patients unable to be randomised within 72 hours after onset of symptoms

  • Requirement for any live viral vaccine in the next 7 days

  • Optional according to specific country legislation:

    • Pregnant, lactating or breastfeeding women

  • ILI, influenza-like illness.