'Risk of bias' assessment of Ahn 2020
Domain	Assessed outcomes	Authors' judgement	Support for judgement
Representative study group (selection bias)	Not available	High	2 participants only
Outcome detectors blinded to intervention (detection bias)	Adverse events	High	Not blinded, awareness of intervention can bias assessment of subjective outcomes
Complete outcome assessment/follow‐up (attrition bias)	Adverse events	Low	Assessed and reported for both cases
Well‐defined study group (reporting bias)	Not available	Low	Population and intervention are well described
Well‐defined outcome (reporting bias)	Adverse events	High	No adverse reaction occurred after the administration of convalescent plasma in both cases. Observation period not reported
Well‐defined risk estimates (analyses)	Adverse events	Not applicable	No analyses performed
Important prognostic factors or follow‐up taken adequately into account (confounding)	Not available	High	Not adjusted for confounding factors