Nafta 1970.

Methods	Randomised, double‐blind, placebo controlled prevention trial of amantadine during the 1969 Hong Kong influenza epidemic in 4 locations in Romania (2 sanatoria, 1 blood transfusion centre and 1 public health department). Treatment was started before influenza activity was recognised. Randomisation is not described but both drugs and placebo were centrally prepared and were indistinguishable apart from a letter C for the active principle and R for placebo
Participants	215 healthy subjects in the 4 trial locations. No withdrawals are reported. Data are reported for all participants by pre‐treatment serological status and study site
Interventions	Oral placebo or amantadine 100 mg twice daily for 20 days
Outcomes	Serological/laboratory: antibody response with paired sera (fourfold or more increase was considered positive) Effectiveness: cases of influenza Cases of ILI (influenza symptoms but no antibody rise) Antibody rise with no influenza symptoms Safety: no adverse events are reported
Notes	The authors conclude that amantadine was highly effective in preventing influenza from Hong/Kong A2 virus and appeared to prevent symptom expression without interfering with the immune response. A well‐reported trial. We assume all participants were healthy
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear