ACE2 and nutritional deficiency disease: Muscle weakness following COVID-19 has been proposed to be multifactorial in aetiology in which systemic inflammation, muscle disuse, hypoxaemia, malnutrition, adverse effects of medication, as well as possible SARS-CoV-2 muscular infiltration via the angiotensin-converting enzyme-2 expressed in human skeletal muscle [29], have been proposed [6].