Thymic Dysfunction and Atrophy in COVID-19 Disease Complicated by Inflammation, Malnutrition and Cachexia

Background: The current COVID-19 pandemic has put millions of people, especially children at risk of protein-energy malnutrition (PEM) by pushing them into poverty and disrupting the global food supply chain. The thymus is severely affected by nutritional deficiencies and is known as a barometer of malnutrition. Aim: The present commentary provides a novel perspective on the role of malnutrition-induced thymic dysfunction, involution and atrophy on the risk and severity of disease in children during the COVID-19 pandemic. Methods: A review of pertinent indexed literature including studies examining the effects of malnutrition on the thymus and immune dysfunction in COVID-19. Results: Protein-energy malnutrition and micronutrient deficiencies of zinc, iron and vitamin A are known to promote thymic dysfunction and thymocyte loss in children. Malnutrition- and infection-induced thymic atrophy and immune dysfunction may increase the risk of first, progression of COVID-19 disease to more severe forms including development of multisystem inflammatory syndrome in children (MIS-C); second, slow the recovery from COVID-19 disease; and third, increase the risk of other infections. Furthermore, malnourished children may be at increased risk of contracting SARS-CoV-2 infection due to socioeconomic conditions that promote viral transmission amongst contacts and create barriers to vaccination. Conclusion: National governments and international organizations including WHO, World Food Program, and UNICEF should institute measures to ensure provision of food and micronutrients for children at risk in order to limit the health impact of the ongoing COVID-19 pandemic.