Importance: There is clinical equipoise for COVID-19 convalescent plasma (CCP) use in patients hospitalized with COVID-19.
Objective: To determine the safety and efficacy of CCP compared with placebo in hospitalized patients with COVID-19 receiving noninvasive supplemental oxygen.
Design, Setting, And Participants: CONTAIN COVID-19, a randomized, double-blind, placebo-controlled trial of CCP in hospitalized adults with COVID-19, was conducted at 21 US hospitals from April 17, 2020, to March 15, 2021.