Innis 1994

Methods	Randomised clinical trial.
Participants	Children age 1 to 16 attending primary school. 40,119 participants were recruited. Of these 38,157 participants entered surveillance and became the analysed cohort.
Interventions	1. Inactivated HAV vaccine (Havrix, SmithKine Beecham) (0,1,12 months). 20,028 participants were randomised to this group. 19,037 participants received all doses as per protocol and entered surveillance. 2. Recombinant HBV vaccine (Engerix‐B, SmithKine Beecham (0,1,12 months). 20,091 participants were randomised to this group. 19,120 participants received all doses as per protocol and entered surveillance.
Outcomes	1. Clinical hepatitis A (signs/symptoms consistent with hepatitis A, alanine aminotransferase levels of 45 U/L or higher, and IgM to HAV). Participants with the disease were identified by evaluating school absences of 2 or more days. 2. Adverse events (anaphylaxis, pain, headache, disturbed sleep, fever, local tenderness, redness/swelling, rash). (Measured in subgroup of 1181 participants). 3. Immunogenicity (anti‐HAV IgG).
Notes	Location: Thailand. Endemicity: high. Follow‐up: 532 days, multiple treatment. Drop out : 6533 participants (33,586/40,119 (84%) at 532 days).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated block randomisation (block size 10).
Allocation concealment (selection bias)	Low risk	A colour code was used to label hepatitis A and control vaccines. Neither parents of participants nor investigators knew the code.
Blinding (performance bias and detection bias) All outcomes	Low risk	Described as double blind with adequate detail provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	The numbers and reasons for dropouts and withdrawals in all intervention groups were described.
Selective reporting (reporting bias)	Low risk	Expected outcomes reported on.
Other bias	Low risk	Trial appears to be free of other sources of bias.