Abstract: medRxiv preprint doi: https://doi.org/10.1101/2021.03.28.21254507; this version posted March 31, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license . Efficacy and safety of convalescent plasma and intravenous immunoglobulin in critically ill COVID-19 patients. A controlled clinical trial. 1 1 Jose Lenin Beltran Gonzalez MD , Mario González Gámez MD , Emmanuel Antonio Mendoza 1 1 1 Enciso MD , Ramiro Josue Esparza Maldonado MD , Daniel Hernández Palacios MD , Samuel 1 1 1 Dueñas Campos MD , Itzel Ovalle Robles MD , Mariana Jocelyn Macías Guzmán MD , Andrea Lucia 1 1 1 García Díaz MD , César Mauricio Gutiérrez Peña MD , Ana Lilian Reza-Escalera MD , Maria Teresa 1 2 3 Tiscareño Gutierrez MD , Elva Galvan-Guerra QFB , Maria del Rocio Dorantes Morales MD , Lucila 4 4 Martínez Medina MD, MSc. , Victor Antonio Monroy Colin MD , Arreola Guerra Jose Manuel MD 1 MSc, PhD . 1. Internal Medicine Department Centenario Hospital Miguel Hidalgo 2. Laboratorio Clinico del Campestre 3. Aguascalientes State Transfusion Center 4. Pediatrics Department Centenario Hospital Miguel Hidalgo Corresponding Authors: José Manuel Arreola Guerra, MD, M. Sc., Ph.D Head, Department of Investigation, Nephrologist, and Associate Professor of Internal Medicine. Hospital Centenario Miguel Hidalgo Av Gómez Morín y Av La Estación, La Alameda, Aguascalientes, Aguascalientes Mexico. C.P. 20259 Tel.: 521 4499946720 dr.jmag@gmail.com Mario Gonzalez Gamez MD Department of Internal Medicine and Infectologist Hospital Centenario Miguel Hidalgo Av Gómez Morín y Av La Estación, La Alameda, Aguascalientes, Aguascalientes Mexico. C.P. 20259 Tel.: 521 4499946720 mariogzg@hotmail.com Summary NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice. medRxiv preprint doi: https://doi.org/10.1101/2021.03.28.21254507; this version posted March 31, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license . Background The proportion of critically ill COVID-19 patients has collapsed hospital care worldwide. The need for alternative therapies for this group of patients is imperative. This study aims to compare the safety and efficacy of convalescent plasma (CP) compared with human immunoglobulin (IVIg) in patients requiring the administration of high oxygen levels or mechanical ventilation. Methods This is a controlled, randomized, open clinical trial of patients with pneumonia secondary to SARS-CoV-2 infection, that fulfilled criteria for severe or critical disease. They were randomized in a 1:2 ratio; group 1 was administered IVIg at a dose of 0.3 grams per kilogram of ideal weight, in an 8- hour infusion every 24 hours, for 5 days. Group 2 was administered 200 ml of CP infused in 2 hours, for 2 days. The primary outcomes were duration of hospitalization and mortality at 28 days. Results: One hundred and ninety (190) patients were randomized; 130 to the CP group, and 60 to the IVIg group. Their average age was 58 years (IQR 47 – 72), and most were male (n= 119, 62.6 %). On inclusion, 85.2 % of patients (n=162) were on..