Virus-specific cellular immunity may be essential for long-term protection against SARS-CoV-2

The major clinical manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection include fever, dry cough, fatigue, and other respiratory symptoms. Recent studies show that over 60% of infected people are asymptomatic carriers who do not even realize they are infected. About 25% of the infected individuals have very mild symptoms and do not require medical treatment. Only about 15% of the individuals infected with the virus, mostly those over 65 with preexisting conditions such as diabetes, hypertension, and obesity, develop serious complications, including acute respiratory distress syndrome (ARDS), secondary infections, and acute heart injury. SARS-CoV-2 can stimulate the human innate immune system leading to the release of cytokines and immune effectors, causing a massive cytokine storm and an acute inflammatory response. This causes increased systemic vascular vulnerability and multiple organ failure. Cytotoxic T lymphocytes specific to specific viral antigens have been found to be effective in controlling viral infection,...