CD40LG and COVID-19: Boxplots of IgM and IgG serological measurements across the groups identified by the results of rapid tests in relation with a qualitative interpretation are described in Fig. 2A. Among patients with a diagnosis of COVID-19, qualitative RDT and serological measurements were evaluated as a function of time from the onset of COVID-19 disease and severity of disease and confirmed a significant association as described in Table 2.