Fig. 4From: Association between convalescent plasma treatment and mortality in COVID-19: a collaborative systematic review and meta-analysis of randomized clinical trialsAccumulation of evidence over time (Cumulative meta-analysis). CI confidence interval, RR risk ratio. Published trials are ordered by their date of publication. For the PLACID trial we used the date when it was first posted as a preprint (September 10th, 2020) before being published in a peer reviewed journal (October 22nd, 2020). Similarly, NCT04479163 was first posted as a preprint (November 21st, 2020) before being published a peer reviewed journal (February 18th, 2021) and RECOVERY Trial was first posted as a preprint (March 10th, 2021) before being published in a peer reviewed journal (May 14th, 2021)Back to article page