Conversely, the effector CD4+ T‐cell population in IAV‐ and SFV + IAV–infected lungs displayed increased levels of both single‐positive and double‐positive CD38+ PD1+ phenotype cells compared with SFV infection at 7 and 10 dpi (Figure 5g and Supplementary figure 3g). The gene discussed is PDCD1; the disease is infection.