The first case of severe SARS-CoV-2 (Severe Acute Respiratory Syndrome-CoronaVirus-2) disease, later named COVID-19 (Corona Virus Disease-19) was reported in the city of Wuhan, China, in January 2020. Subsequently, the viral infection and disease spread rapidly to many geographical areas of the world. In March 2020, the disease was recognised as a pandemic by the World Health Organisation (WHO). By 23 March 2021, just under 125,000,000 confirmed cases had been recorded worldwide since the start of the pandemic, with 2,727,837 deaths. As is known, in Italy and in a large part of the planet, also in relation to the infection containment measures adopted by different countries, the infection and the disease have been characterised by successive waves. Patients with COVID-19 typically present with signs and symptoms of severe infectious respiratory disease, increased leukocytes and frequent lymphocytopenia. Interstitial pneumonia of variable severity is also usually evident. A considerable proportion of individuals infected by SARS-CoV-2 may actually remain asymptomatic or develop very mild symptoms. Conversely, a not insignificant proportion of individuals develop such severe disease that they require hospitalisation. Approximately 20% of these individuals present with respiratory conditions requiring transfer to an Intensive Care Unit (ICU). Mortality among these patients can be very high, particularly those from older age groups with significant comorbidities.