ab Wright 1976a

Methods	2 studies are reported in the paper: RCT conducted on infants to determine safety and reactogenicity of monovalent flu inactivated vaccine (Wright 1976 2) Placebo‐controlled cohort study carried out on preschool children (Wright 1976 1)
Participants	33 preschool children aged 3 to 6 were enrolled in the other study 35 children enrolled in the Paediatric Vaccine Clinic at Vanderbilt Hospital (Nashville, Tennessee) aged between 12 and 28 months
Interventions	Study participants received randomly a single dose of 0.25 ml of monovalent inactivated flu vaccine B/Hong Kong/5/72 (zonally purified, Eli Lilly and Company) containing at least 250 CCA units per dose or saline control at the time of a routine clinic visit. Vaccine or placebo were administered during a routine clinical visit. Wright 1976 1 was conducted on preschool children, participants from 1 classroom received all 1 dose of vaccine. Eight children from another classroom consisting of 12 participants received vaccine, whereas the remaining 4 were given saline solution in double‐blind manner. Three of these 4 controls received 1 dose of vaccine 6 weeks later. Study participants received randomly a single dose of 0.25 ml of monovalent inactivated flu vaccine B/Hong Kong/5/72 (zonally purified, Eli Lilly and Company) containing at least 250 CCA units per dose or saline control at the time of a routine clinic visit. Vaccine or placebo were administered during a routine clinical visit
Outcomes	Serological Hemagglutinin inhibition antibody test against 4 units of Flu/B/HK/8/73 antigen Effectiveness N/A Safety Parents of the children completed a questionnaire to record local and systemic reactions so as the temperature at 20:00 on the day of vaccination. Parents were unaware if the children received immunisation
Funding Source	Industry
Notes	Parents of the children completed a questionnaire to record local and systemic reactions so as the temperature at 20:00 on the day of vaccination. Parents were unaware if the children received immunisation
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	High risk	Not used
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Single
Incomplete outcome data (attrition bias) All outcomes	Low risk	No losses to follow‐up
Summary assessments	High risk	Insufficient information to assess study design