Schapira 1971.

Methods	The study is a placebo‐controlled trial of amantadine conducted in the Northern English village of Keighly by one general practitioner during the pandemic of the winter of 1968 to 1969. Follow up was 10 days
Participants	297 healthy volunteers from firms, schools, a newspaper, a bank and families. Participants' mean age was evenly matched at 38 years (active arm) and 38.5 years (placebo arm). All participants' sera were screened prior to commencement and those who complained of symptoms of influenza underwent a second antibody titre estimation against A2/Hong Kong/1/68, the prevalent strain at the time. As it is likely that some participants were already infected prior to commencement the authors point out that the trial is both prophylaxis and treatment
Interventions	Participants were allocated to receive either amantadine 100 mg every 12 hours (157 participants) or an oil‐based placebo capsule (140 participants), identified only by a code
Outcomes	Laboratory: paired sera Efficacy: ILI or influenza Adverse effects are not reported
Notes	The authors conclude that the trial provides "marginal" evidence of prophylactic effect of amantadine. The practices of randomisation and allocation are not described, making it impossible to assess methodological rigour, although the similar numbers of participants in each arm led us to consider this a randomised trial. Allocation concealment appeared adequate. 49 out of the 157 volunteers in the treatment arm suffered influenza symptoms compared to 39 out 140 on the placebo arm. However, only 8 and 15 cases respectively were serologically confirmed as influenza (Table 3). 12 paired sera were unavailable for the 49 symptomatic volunteers in the treatment arm and 3 paired sera were unavailable although the authors do not explain the reason for the drop‐outs
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear