Dowd 1966.

Methods	Double‐blind, no ITT
Participants	Army recruits, USA
Interventions	Ampicillin: 30 x 500 mg versus oral penicillin G: 30 x 462 mg versus placebo
Outcomes	Eradication, serogroup of eradication failure, resistance developed Follow‐up: 26 days
Notes	Main serogroup: B
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	Unclear
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No ITT
Selective reporting (reporting bias)	Low risk	No evidence
Other bias	Low risk	No evidence