Abstract: Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. Medicine in Drug Discovery 8 (2020) 100064 Contents lists available at ScienceDirect Medicine in Drug Discovery journal homepage: https://www.journals.elsevier.com/medicine-in-drug-discovery Original Clinical Research Report Serum Levels of Vitamin C and Vitamin D in a Cohort of Critically Ill COVID19 Patients of a North American Community Hospital Intensive Care Unit in May 2020: A Pilot Study☆ ⁎ Cristian Arvinte, MD a, , Maharaj Singh, PhD b,c, Paul E. Marik, MD, FCCP, FCCM d Intensivist & Pulmonologist, North Suburban Medical Center, Thornton, Colorado 80229, USA Research Assistant Professor, Biostatistics, Research and Graduate Studies, Marquette University, School of Dentistry, Milwaukee, Wisconsin 53201, USA Biostatistician Senior, Advocate Aurora Research Institute, Advocate Aurora Health Care, Milwaukee, Wisconsin, 53233, USA d Chief, Pulmonary and Critical Care Medicine, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA a b c A R T I C L E I N F O Article history: Received 11 August 2020 Received in revised form 29 August 2020 Accepted 9 September 2020 Available online 18 September 2020 Keywords: COVID-19 SARS-CoV-2 Critical illness Intensive care unit (ICU) Serum vitamin C Serum vitamin D Age Body mass index (BMI) HbA1c (glycated hemoglobin) A B S T R A C T Background: The COVID-19 pandemic has placed an enormous and growing burden on the population and health infrastructure, warranting innovative ways to mitigate risk of contracting and developing severe forms of this disease. A growing body of literature raises the issue of vitamin C and vitamin D as a risk-assessment tool, and therapeutic option, in COVID-19. Objective: The objective of this pilot study was to measure serum vitamin C and vitamin D levels in a cohort of patients with critical COVID-19 illness in our community hospital ICU, correlate with other illness risk factors (age, BMI, HgbA1c, smoking status), generate hypotheses, and suggest further therapeutic intervention studies. Method: This pilot study included all 21 critically ill COVID-19 patients hospitalized in May 2020 in the ICU of North Suburban Medical Center, Thornton, Colorado, in whose care the principal investigator (C.A.) was involved. We measured patients’ serum vitamin C and vitamin D levels, and standard risk factors like age, BMI, HbA1c, and smoking status. Variables in this study were gauged using descriptive statistics. Results: Of 21 critically ill COVID-19 patients (15 males and 6 females, 17 Hispanic and 4 Caucasian, of median age 61 years, range 20–94), there were 11 survivors. Serum levels of vitamin C and vitamin D were low in most of our critically ill COVID-19 ICU patients. Older age and low vitamin C..