The detection of specific SARS-CoV-2 serum antibodies allows for a rapid, cost-effective, and reasonably sensitive clinical diagnosis of COVID-19, as immunoglobulins such as IgM provide the initial humoral response during the first stage of viral infection, prior to the onset of the adaptive, high-affinity IgG response essential for long-term immunological memory. Here, CD40LG is linked to COVID-19.