CD40LG and COVID-19: Testing for the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19) broadly falls into two categories: (1) reverse transcription polymerase chain reaction (RT-PCR) testing for active infection (i.e., diagnostic testing) and (2) immunoglobulin G or M (IgG or IgM) antibody testing for SARS-CoV-2 antibodies.