IFNL1 and infection: Consistent with previous reports, our study showed that although AECs from young donors produced more IL-29 after infection with H1N1 epidemic strain Cal04 or lab-adapted H1N1 strain PR8 than AECs from adult or older donors, they still supported higher H1N1 replication and weak responsiveness to antiviral treatment with IL-29 (Figure 3, Supplementary Figure 1).