Selenium serum levels in patients with SARS-CoV-2 infection: a systematic review and meta-analysis

The nutritional status is a determinant of the immune response that promotes a cellular homeostasis. In particular, adequate selenium levels lead to a better antioxidant and immune response. The aim of this work is to assess whether blood selenium levels, at time of SARS-CoV-2 infection, have an impact on the development and severity of COVID-19. A systematic review and meta-analysis of comparative and descriptive studies using MeSH terms, selenium and COVID-19 was performed. We searched bibliographic databases up to 17 July 2022 in PubMed and ScienceDirect. Studies that reported data on blood selenium levels were considered. A total of 629 articles were examined by abstract and title, of which 595 abstracts were read, of which 38 were included in the systematic review and 11 in the meta-analysis. Meta-analysis was conducted to mean difference (MD) with a 95 % confidence interval (CI), and heterogeneity was tested by I-2 with random factors with a MD between selenium levels, mortality, morbidity and healthy subjects with a P-value of 0.05. Selenium levels were higher in healthy people compared to those in patients with COVID-19 disease (six studies, random effects MD: test for overall effect Z = 3.28 (P = 0.001), 97 % CI 28.36 (11.41-45.31), P < 0.00001), but without difference when compared with the degree of severity in mild, moderate or severe cases. In conclusion, the patients with active SARS-CoV-2 infection had lower selenium levels than the healthy population. More studies are needed to evaluate its impact on clinical severity through randomised clinical trials.