The adaptive immune system, regulated by CD4 T cells, is essential for control of many viral infections. Endemic coronavirus infections generally occur as short-term upper respiratory tract infections which in many cases appear to be cleared before adaptive immunity is fully involved, since adaptive immunity takes approximately 1.5–2 weeks to ramp up the response to a primary infection, or approximately 1 week for a recurrent infection. However, the adaptive immune response to SARS-CoV-2 infection will be critical to full recovery with minimal long-lasting effects, and to either prevention of recurrence of infection or at least reduced severity of symptoms. The detailed kinetics of this infection versus the dynamics of the immune response, including in vaccinated individuals, will largely determine these outcomes.

由CD4 T细胞调节的适应性免疫系统对于控制许多病毒感染至关重要。地方性冠状病毒感染通常以短期上呼吸道感染发生，在许多情况下似乎已完全消除适应性免疫，因此已被清除，因为适应性免疫大约需要1.5–2周才能增强对原发感染的反应，或大约1一周内反复感染。但是，对SARS-CoV-2感染的适应性免疫反应对于全面恢复且持久作用最小至关重要，并且对于预防感染复发或至少减轻症状的严重程度至关重要。这种感染的详细动力学与免疫反应的动力学，包括在接种疫苗的个体中的动力学，将在很大程度上决定这些结果。