Chapter 37: SARS-CoV-2 Infection and COVID-19 Disease

Epidemiological concepts frame pandemic severity through the basic reproduction number, which quantifies how readily the virus spreads within populations and predicts transmission dynamics. Clinical disease manifestations span a wide spectrum from entirely asymptomatic infections to critical respiratory dysfunction, with progression typically beginning four days after viral exposure and potentially advancing to severe lower respiratory tract involvement requiring intensive care. Age emerges as a critical predictor of disease severity, with older individuals facing substantially higher risks of complicated illness and mortality. Diagnostic approaches are evaluated across three distinct methodologies: polymerase chain reaction testing offers superior sensitivity for detecting active infection, rapid antigen assays provide quick preliminary identification, and serological testing identifies previous exposure through antibody detection patterns. Imaging findings, particularly bilateral ground-glass opacities on computed tomography, characterize the typical pneumonic pattern. Management strategies encompass multiple therapeutic categories including direct-acting antivirals that inhibit viral replication, immunomodulatory agents like corticosteroids and engineered antibodies that regulate inflammatory responses, and supportive interventions addressing downstream complications such as aberrant blood clotting and opportunistic bacterial superinfection. Prevention through vaccination represents a critical public health strategy, with available platforms utilizing distinct immunological approaches including messenger ribonucleic acid technology, replication-competent viral vectors, recombinant protein formulations, chemically inactivated virions, and attenuated live vaccine candidates. Infection prevention relies on physical barriers including respiratory protective equipment and source control measures to reduce transmission risk in healthcare and community settings.