It is already known that Coronavirus disease 2019 (COVID-19) may lead to various degrees and forms of lung parenchyma damage, but some cases take a strikingly severe course that is difficult to manage. We report the case of a 62-year old male, non-obese, non-smoker, and non-diabetic, who presented with fever, chills, and shortness of breath. The infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was diagnosed by real-time Polymerase Chain Reaction. Although the patient had been vaccinated with 2 doses of Pfizer-BioNTech COVID-19 vaccine 7 months earlier and had no risk factors for a severe outcome, serial computed tomography (CT) scan revealed lung involvement progressively extending from an initial 30% to 40% to almost 100% 2.5 months later. The spectrum of lung lesions included at first only ground-glass opacities and some tiny emphysema bullae, but later also bronchiectasis, pulmonary fibrosis, and large emphysema bullae as post-COVID-19 pulmonary sequelae. For fear of severe evolution of superimposed bacterial infection (Clostridoides difficile enterocolits and possibly bacterial pneumonia) the administration of corticosteroids was intermittent. Massive right pneumothorax secondary to bulla rupture, possibly favored by the indispensable high flow oxygen therapy, led to respiratory failure compounded by hemodynamic instability, and ultimately to the patient's final demise. COVID-19 pneumonia may cause severe lung parenchyma damage which requires long-term supplemental oxygen therapy. Beneficial or even lifesaving as it might be, high flow oxygen therapy may nonetheless have deleterious effects too, including the development of bullae that may rupture engendering pneumothorax. Corticosteroid treatment should probably be pursued despite superimposed bacterial infection to limit the viral induced damage to lung parenchyma.