CD4 and COVID-19: Thus, although the repertoire of the cellular immune response directed against SARS-CoV-2 is wider in recently infected patients (Fig. 2C and D, 2H to I), the minimal increase in cellular effectors (p=0.240 for CD8+ T cells, Fig. 2E and p=0.158 for CD4+ T cells, Fig. 2J) is unlikely to account alone for the drastic advantage in term of protection against symptomatic COVID-19 observed in this group as compared with vaccinated transplant recipients.