Abstract: nutrients Article Prevalence of Micronutrient Deficiencies in Patients Hospitalized with COVID-19: An Observational Cohort Study Manyola Voelkle 1,2 , Claudia Gregoriano 1 , Peter Neyer 3 , Daniel Koch 1 , Alexander Kutz 1 , Luca Bernasconi 3 , Anna Conen 2,4 , Beat Mueller 1,2 and Philipp Schuetz 1,2, * 1 2 3 4 * Citation: Voelkle, M.; Gregoriano, C.; Neyer, P.; Koch, D.; Kutz, A.; Bernasconi, L.; Conen, A.; Mueller, B.; Schuetz, P. Prevalence of Micronutrient Deficiencies in Patients Hospitalized with COVID-19: An Observational Cohort Study. Nutrients 2022, 14, 1862. https:// doi.org/10.3390/nu14091862 Academic Editors: Omorogieva Ojo and Amanda R Amorim Adegboye Received: 30 March 2022 Accepted: 26 April 2022 Published: 29 April 2022 Medical University Department of Medicine, Kantonsspital Aarau, 5001 Aarau, Switzerland; manyola.voelkle@ksa.ch (M.V.); claudia.gregoriano@ksa.ch (C.G.); daniel.koch@ksa.ch (D.K.); alexander.kutz@ksa.ch (A.K.); beat.mueller@ksa.ch (B.M.) Faculty of Medicine, University of Basel, 4056 Basel, Switzerland; anna.conen@ksa.ch Institute of Laboratory Medicine, Kantonsspital Aarau, 5001 Aarau, Switzerland; peter.neyer@ksa.ch (P.N.); luca.bernasconi@ksa.ch (L.B.) Department of Infectious Diseases and Infection Prevention, Kantonsspital Aarau, 5001 Aarau, Switzerland Correspondence: schuetzph@gmail.com; Tel.: +41-62-838-9524 Abstract: Background: A higher risk for severe clinical courses of coronavirus disease 2019 (COVID-19) has been linked to deficiencies of several micronutrients. We therefore studied the prevalence of deficiencies of eight different micronutrients in a cohort of hospitalized COVID-19-patients. Methods: We measured admission serum/plasma levels of vitamins A, B12, D, and E, as well as folic acid, zinc, selenium, and copper in 57 consecutively admitted adult patients with confirmed COVID-19 and analyzed prevalence of micronutrient deficiencies and correlations among micronutrient levels. Further, we studied associations of micronutrient levels with severe disease progression, a composite endpoint consisting of in-hospital mortality and/or need for intensive care unit (ICU) treatment with logistic regression. Results: Median age was 67.0 years (IQR 60.0, 74.2) and 60% (n = 34) were male. Overall, 79% (n = 45) of patients had at least one deficient micronutrient level and 33% (n = 19) had ≥3 deficiencies. Most prevalent deficiencies were found for selenium, vitamin D, vitamin A, and zinc (51%, 40%, 39%, and 39%, respectively). We found several correlations among micronutrients with correlation coefficients ranging from r = 0.27 to r = 0.42. The strongest associations with lower risk for severe COVID-19 disease progression (adjusted odds ratios) were found for higher levels of vitamin A (0.18, 95% CI 0.05–0.69, p = 0.01), zinc (0.73, 95% CI 0.55–0.98, p = 0.03), and folic acid (0.88, 95% CI 0.78–0.98, p = 0.02). Conclusions: We found a high prevalence of micronutrient deficiencies in mostly older patients hospitalized for COVID-19, particularly regarding selenium, vitamin D, vitamin A, and zinc. Several deficiencies were associated with a higher risk for more severe COVID-19 courses. Whether supplementation of micronutrients is useful for prevention of severe clinical courses or treatment of COVID-19 warrants further research. Keywords: COVID-19; micronutrients; deficiency; SARS-CoV-2; hospital outcomes Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published..