CD40LG and COVID-19: Although many commercial assays have been developed for the clinical diagnosis of SARS-CoV-2 infection, the advantage of research-use assays for COVID-19 vaccine and prophylaxis studies is that antibody titer can be quantified and differentiated for different isotypes (IgG, IgA, and IgM) as well as different targets (RBD, N, NTD, S1, S2, total S).