'Risk of bias' assessment of Jin 2020
Domain	Assessed outcomes	Authors' judgement	Support for judgement
Representative study group (selection bias)	Not available	High	6 of 146 COVID‐19 patients in Guizhou Jiangjunshan Hospital who received convalescent plasma therapy included in report
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	Unclear	Assessed for all participants over study period, observation period unclear
Well‐defined study group (reporting bias)	Not available	Unclear	Study population well described, but intervention scarcely described
Well‐defined outcome (reporting bias)	Adverse events	High	Reported for all participants, but observation period unclear
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, results only reported for 6 of 146 participants receiving convalescent plasma