HTRA1 and influenza: We describe influenza-induced redox imbalances in the LRT to which pneumococci adapt by inducing the pneumococcal surface protease/chaperone high temperature requirement A (HtrA), that helps the bacteria to grow under oxidative stress condition in vitro and in vivo, and protects them from host-mediated opsonophagocytosis by maintaining capsular production (Sender et al., 2020).