aa Eddy 1970.

Methods	Controlled clinical trial, single‐blind, conducted in South Africa during the 1969 influenza season. Follow‐up lasted from May to July. The first clinical case of influenza appeared on 21 May 1969 and the last 6 weeks later. The epidemic period lasted 6 weeks. The control participants were selected by drawing a 1‐in‐4 systematic sample from a ranked list of the personnel numbers.
Participants	1758 healthy male black African employees: 1254 treated and 413 placebo. Age of participants was 18 to 65.
Interventions	Monovalent inactivated parenteral vaccine. Schedule and dose were single injection, 1 mL. Vaccine composition was: A2/Aichi/2/68 (Hong Kong variant). Placebo was sterile water. Vaccine was recommended and matched circulating strain.
Outcomes	Influenza‐like illness, working days lost, days ill. Influenza‐like illness was not defined; case features were generically described in results section. All ill people were admitted to hospital until recovery. Surveillance was passive.
Notes	The word 'double‐blinding' was not used, but the control group received an injection of "dummy vaccine". Poor reporting, poor‐quality study. Circulating strain was A2/Hong Kong/68 virus. Efficacy data only were extracted. Industry funded
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Systematic selection
Allocation concealment (selection bias)	High risk	Inadequate
Blinding (performance bias and detection bias) All outcomes	High risk	No descriptions
Incomplete outcome data (attrition bias) All outcomes	High risk	Insufficient description
Summary assessment	High risk	High risk of bias