West 2001.

Methods	Study design: open‐label, randomised trial Setting: 3 sites, USA Study dates: not reported
Participants	Sample size: 126 healthy infants Dropouts/withdrawals: 5 infants did not receive all 3 vaccines. Age: not reported Sex: male = 72, female = 54 Inclusion criteria: "Healthy infants approximately 2 months of age, who had previously received a dose of monovalent HB vaccine shortly after birth and had a negative history for both Hib disease and HBV infection, were recruited for the study" (quote) Exclusion criteria: not reported
Interventions	2 treatment groups one in which infants were given diphtheria‐tetanus‐pertussis whole cell vaccine (DTP) + IPV at two months followed by two OPV doses and the other group received DTP + OPV at 2 months followed by two further OPV doses Group 1 (DTP + IPV): (n = NR): IOO at 2, 4, 6, months Group 2 (DTP + OPV): (n = NR): OOO at 2, 4, 6, months
Outcomes	Antibody responses against poliovirus types 1, 2 and 3 Adverse events. Parents or guardians were given report cards and asked to record daily any injection site or systemic adverse events. Timing of outcome assessment: 6 months Follow‐up: 14 months
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Infants were randomly allocated (1 : 1) to 1 of 2 treatment groups designated DTP/IPV and DTP+OPV"
Allocation concealment (selection bias)	Unclear risk	Comment: not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Comment: no blinding but performance is not likely to be influenced by lack of blinding in terms of intervention or co‐interventions
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Comment: no blinding but objective outcome (antibody titres) is not likely to be influenced by lack of blinding
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: not reported
Selective reporting (reporting bias)	Low risk	Comment: no evidence of selecting reporting
Other bias	Low risk	Comment: no evidence of other bias
Conflict of interest	Unclear risk	This study was supported financially by the Merck Research Laboratories.