This is particularly relevant to acute viral respiratory infection as it has been previously shown that the number of GrB-positive/perforin-negative cells in the lungs and levels of GrB in bronchoalveolar lavage fluid are elevated in patients with acute respiratory distress syndrome Rasmuson et al. (2016) Recently, plasma levels of GrB were identified as one of six key inflammatory analytes in critically ill coronavirus disease 2019 patients (Fraser et al., 2020). Here, GZMB is linked to acute respiratory distress syndrome.