The importance of determining the amount of 'therapeutic units' before using convalescent plasma.

"Financial & competing interests disclosure: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brasil – finance code 001. National Council for Scientific and Technological Development (CNPq). This work was supported by grants from the Rio de Janeiro State Research Foundation (FAPERJ). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.: No writing assistance was utilized in the production of this manuscript."

"Financial & competing interests disclosure: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brasil – finance code 001. National Council for Scientific and Technological Development (CNPq). This work was supported by grants from the Rio de Janeiro State Research Foundation (FAPERJ). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.: No writing assistance was utilized in the production of this manuscript."