CD40LG and COVID-19: In summary, while differences of the experimental methodology and/or patient cohorts might account for the discrepancy of findings on the characterization of immunodominant epitopes of SARS-CoV-2, our data indicate that during the first weeks of COVID-19 an IgM- and IgG-specific antibody response is raised in a significant portion of COVID-19 patients to the N- and C-terminal ends of the M protein with almost identical levels as observed for epitopes located in the S and N protein.