It is today acknowledged that an adequate nutritional status is crucial for the development, maintenance, and expression of the immune response [5,6]. Micronutrients (i.e., vitamins and nutritionally essential minerals) influence and support every stage of the immune response. Deficiencies of micronutrients can affect both innate and adaptive immunity, causing immunosuppression and thus increasing the susceptibility to infections. In addition, mucosal-associated invariant T cells (MAIT), which are innate-like T cells expressing a semi-invariant T cell receptor, play a role in polarizing adaptive lymphocyte function, and contribute to metabolic dysfunction [7]. Furthermore, infections and an inadequate nutritional status have a synergistic relationship. The immune response itself to an infection exacerbates a poor nutritional state and causes an increase in the demand for micronutrients [8,9]. Viral infections are a leading cause of morbidity and mortality worldwide [10], as is shown by both seasonal influenza, and the recent outbreak of coronavirus disease 2019 (COVID-19), caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [11].