2003). The number of CD4+ and CD8+ T cells as humoral responses significantly reduced in the peripheral blood of infected patients with SARS-CoV2 (Xu et al. 2020). Similarly, reduction of CD4+ and CD8+ T cells in the acute phase of infection with SARS-CoV is also associated with reduction in the number of CD4+ and CD8+ T cells (Fan et al. 2009). Moreover, CD8+ T cells also showed a similar effect in infected mice with MERS-CoV (Zhao et al. 2014). Here, CD4 is linked to infection.