SARS-CoV-2 is an enveloped, positive-sense, single-stranded RNA virus of the Coronaviridae family. It is a large RNA virus, with a genome of approximately 30 kb. While most human coronaviruses typically cause mild disease, SARS-CoV-2 has led to a global public health crisis.
The virus enters host cells via the ACE2 receptor, a process mediated by the viral spike (S) protein. The receptor-binding domain of the spike protein attaches to host cell receptors, allowing the virus to infect respiratory tract cells and, in some cases, other tissues.
Transmission occurs through respiratory droplets, aerosols, and contact with contaminated surfaces. Asymptomatic or pre-symptomatic individuals can transmit the virus, making containment efforts more difficult.
During the pandemic, multiple variants of concern emerged, with mutations that altered transmissibility and disease severity. For example, the Delta variant was associated with more severe disease, while Omicron variants were more transmissible.
Symptoms of SARS-CoV-2 infection vary significantly depending on the individual and the viral variant. Common symptoms include:
Severe cases may progress to pneumonia, acute respiratory distress syndrome, and multi-organ failure. Hospitalized patients may require oxygen supplementation or mechanical ventilation.
During the pandemic, treatment options included corticosteroids such as dexamethasone, monoclonal antibodies (e.g., casirivimab and imdevimab, marketed as REGEN-COV), and antiviral agents.
Preventive measures include vaccination, mask use, hand hygiene, and physical distancing. The rapid development and deployment of nucleic acid-based vaccines played a critical role in reducing severe disease and mortality during the COVID-19 pandemic.
Several antiviral treatments and monoclonal antibodies have proven effective in managing severe disease, particularly in high-risk populations.
