COVID-19 Basics

SARS-CoV-2 infects respiratory epithelial cells through ACE2 receptors. The resulting immune response can inflame the airways and alveoli, producing cough, sputum, and impaired gas exchange. When alveolar injury becomes diffuse, fluid and inflammatory debris interfere with oxygen movement across the alveolar-capillary membrane. The lungs become less compliant, and viral pneumonia can progress to acute respiratory distress syndrome (ARDS). That mechanism explains why oxygenation matters more than fever alone when judging severity. A patient may report only fatigue and cough while developing falling oxygen saturation. Conversely, fever can be high without severe respiratory compromise. The nurse therefore links symptoms to respiratory function: work of breathing, respiratory rate, ability to speak, mental status, and oxygen saturation.