When comparing pre-to post-boost responses, patients with cancer presented with a significant increase of their spike-specific IgG levels (13.9-fold on average for Ttx and 10.6-fold for Tut) and CD4+ T cell frequencies (4.3--fold on average for Ttx and 3.1-fold for Tut), with a similar trend but a large proportion of non-responders observed regarding the spike-specific CD8+ T cell reactivity (Figure 2A; analysis results and statistical parameters are provided in Table S2). Here, CD4 is linked to cancer.