CD40LG and COVID-19: While the gold standard for acute COVID-19 diagnosis remains the detection of SARS-CoV-2 virus in respiratory tract swab specimens by RT-PCR [2], serological tests detecting Abs, immunoglobulin G (IgG), and immunoglobulin M (IgM) may identify patients who have been infected in the past, including prior asymptomatic infections, and can be used to measure herd immunity to the disease [3].