Correlating with the lack of effective immunity, the high in vitro CD4+/CD8+/NK cell infection rates (10.4–26.8%) persisted for those who succumbed (Fig. 3i–k), while the infection rate fall for CD8+ T cells (d18 for R1, d14 and d22 for R2 and d22 and d30 for R3) was directly related to recovery (Fig. 3i) and inversely correlated with H7N9-specific CTL and TH frequencies. The gene discussed is CD4; the disease is infection.