Salivary lysozyme concentration, secretion, and osmolarity-adjusted concentration in International Space Station (ISS) crewmembers and ground-based control subjects (A) and rookie and veteran crew (B) during an ISS mission. Values are means ± SE. Time points are n days before launch (L−n), n days into flight (FDn), and n days after return to Earth (R+n). No differences were found between viral shedders and nonshedders (data not shown). Differences between groups: #P < 0.05, ##P < 0.01. *Differences between specific time points indicated by bars, colored to indicate specific group effect.