CD84 and COVID-19: We aimed to define CD84 dynamics in patient cohorts of respiratory disease and immune cell populations in influenza virus-infected mice.<h4>Methods</h4>Expression dynamics of <i>CD84</i> and association with previously identified correlates of severe and fatal respiratory disease outcomes, <i>OLAH</i> and <i>IL18R1</i>, were analysed in A(H7N9) and COVID-19 patient cohorts across disease severities.